485BPOS

Filed with the Securities and Exchange Commission on March 13, 2020

1933 Act Registration File No. 033-20827

1940 Act Registration File No. 811-05518

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933		[	X	]
Pre-Effective Amendment No.		[		]
Post-Effective Amendment No.	262	[	X	]

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940		[	X	]
Amendment No.	266	[	X	]

(Check Appropriate Box or Boxes)

THE RBB FUND, INC.

(Exact Name of Registrant as Specified in Charter)

615 East Michigan Street

Milwaukee, Wisconsin 53202

(Address of Principal Executive Offices, including Zip Code)

Registrant’s Telephone Number, including Area Code: (609) 731-6256

Copies to:

SALVATORE FAIA	MICHAEL P. MALLOY, ESQUIRE
The RBB Fund, Inc.	Faegre Drinker Biddle & Reath LLP
615 East Michigan Street	One Logan Square, Suite 2000
Milwaukee, Wisconsin 53202	Philadelphia, Pennsylvania 19103-6996

Approximate Date of Proposed Public Offering: As soon as practicable after the Registration Statement becomes effective.

[	X	]	immediately upon filing pursuant to paragraph (b)
[		]	on (date) pursuant to paragraph (b)
[		]	60 days after filing pursuant to paragraph (a)(1)
[		]	on (date) pursuant to paragraph (a)(1)
[		]	75 days after filing pursuant to paragraph (a)(2)
[		]	on (date) pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

[ ] This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

This Post-Effective Amendment (“PEA”) No. 262 to the Registration Statement for The RBB Fund, Inc. (the “Company”) on Form N-1A hereby incorporates Parts A, B and C from the Company’s PEA No. 261 on Form N-1A filed on February 28, 2020. This PEA No. 262 is filed for the sole purpose of submitting the XBRL exhibits for the risk/return summaries first provided in PEA No. 261 to the Company’s Registration Statement.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “1933 Act”), and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Post-Effective Amendment to its Registration Statement under Rule 485(b) under the 1933 Act and has duly caused this Post-Effective Amendment to its Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Chadds Ford, and Commonwealth of Pennsylvania on March 13, 2020.

THE RBB FUND, INC.
By:	/s/ Salvatore Faia
	Salvatore Faia
	President

Pursuant to the requirements of the 1933 Act, this Amendment to Registrant’s Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

SIGNATURE	TITLE	DATE
/s/ Salvatore Faia	President (Principal Executive Officer) and Chief Compliance Officer	March 13, 2020
Salvatore Faia
/s/ James G. Shaw	Treasurer (Chief Financial Officer)	March 13, 2020
James G. Shaw	and Secretary
*J. Richard Carnall	Director	March 13, 2020
J. Richard Carnall
*Julian A. Brodsky	Director	March 13, 2020
Julian A. Brodsky
*Arnold M. Reichman	Director	March 13, 2020
Arnold M. Reichman
*Robert Sablowsky	Director	March 13, 2020
Robert Sablowsky
*Robert Straniere	Director	March 13, 2020
Robert Straniere
*Nicholas A. Giordano	Director	March 13, 2020
Nicholas A. Giordano
*Gregory P. Chandler	Director	March 13, 2020
Gregory P. Chandler
*Brian T. Shea	Director	March 13, 2020
Brian T. Shea

*By: /s/ Salvatore Faia

Salvatore Faia

Attorney-in-Fact

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Julian A. Brodsky, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Julian A. Brodsky
	Julian A. Brodsky

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, J. Richard Carnall, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ J. Richard Carnall
	J. Richard Carnall

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Nicholas A. Giordano, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Nicholas A. Giordano
	Nicholas A. Giordano

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Arnold M. Reichman, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Arnold M. Reichman
	Arnold M. Reichman

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Robert Sablowsky, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Robert Sablowsky
	Robert Sablowsky

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Robert A. Straniere, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 16, 2017
	/s/ Robert Straniere
	Robert Straniere

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Gregory P. Chandler, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	February 17, 2017
	/s/ Gregory P. Chandler
	Gregory P. Chandler

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Brian T. Shea, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw, Edward Paz, and Robert Amweg, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	May 10, 2018
	/s/ Brian T. Shea
	Brian T. Shea

INDEX TO EXHIBITS

Exhibit	Exhibit No.
Instance Document	EX-101.INS
Schema Document	EX-101.SCH
Calculation Linkbase Document	EX-101.CAL
Definition Linkbase Document	EX-101.DEF
Label Linkbase Document	EX-101.LAB
Presentation Linkbase Document	EX-101.PRE

XML

Label

Element

Value

Prospectus [Line Items]

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Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Matson Money | Matson Money International Equity VI Portfolio

Prospectus [Line Items]

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Risk/Return [Heading]

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MATSON MONEY INTERNATIONAL EQUITY VI PORTFOLIO FMVIX

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The Matson Money International Equity VI Portfolio (for this section only, the “Portfolio”) seeks long-term capital appreciation.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Portfolio. This table does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, overall fees and expenses would be higher.

Operating Expenses Caption [Text]

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Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Portfolio shares are held in a taxable account. These costs, which are not reflected in Total Annual Portfolio Operating Expenses or in the Example, affect the Portfolio’s performance. During the fiscal year ended August 31, 2019, the Portfolio’s portfolio turnover rate was 13% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

13.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total Annual Portfolio Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. This Example does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, the costs shown below would be higher.

The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Portfolio pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in equity securities, such as common stocks, preferred stocks or securities convertible into stocks, of foreign companies, or invest substantially all of their assets in such equity securities. The Portfolio will diversify its investments by investing primarily in investment companies that focus on different segments of the foreign equity markets, including emerging markets, with little or no focus on domestic equity markets. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Portfolio’s net assets to be invested in the securities of investment companies, including other investment companies funded by insurance company separate accounts, that invest in the types of securities described in each asset class below, with less than 5% of the net assets invested in cash or money market instruments.

International Small Cap Value Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of small companies in foreign countries with developed markets that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios, as well as economic conditions and developments in the issuer’s industry. The criteria used for assessing value are subject to change from time to time. The underlying investment adviser(s) determine the maximum market capitalization of a small company with respect to each country. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Large Cap Value Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of large companies in foreign countries with developed markets that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios, as well as economic conditions and developments in the issuer’s industry. The criteria used for assessing value are subject to change from time to time. The underlying investment adviser(s) determine the minimum market capitalization of a large company with respect to each country or region. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Small Company Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of small companies in foreign countries with developed markets. The underlying investment adviser(s) determine the maximum market capitalization of a small company with respect to each country. This threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Large Cap Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of large companies in foreign countries with developed markets. The underlying investment adviser(s) determine the minimum market capitalization of a large company with respect to each country or region. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

Emerging Markets Asset Class, Emerging Markets Value Asset Class, and Emerging Markets Small Cap Asset Class (collectively, the “Emerging Markets Asset Classes”): Underlying investment companies comprising each Emerging Markets Asset Class generally will purchase stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of companies located in emerging market countries, including frontier markets (emerging market countries in an earlier stage of development). The underlying investment companies investing in securities of the Emerging Markets Asset Class and the Emerging Markets Small Cap Asset Class will generally purchase the equity securities of larger and smaller companies, respectively, within each country. The underlying investment adviser(s) determine company size primarily based on market capitalization. The thresholds will vary by country or region, and the dollar amounts will change from time to time due to market conditions.

The underlying investment companies in the Emerging Markets Value Asset Class generally will purchase emerging market equity securities that are deemed by the underlying investment adviser(s) to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time.

The underlying investment companies may use derivatives, such as futures contracts and options on futures contracts for equity securities and indices, to hedge currency exposure or to adjust market exposure based on actual or expected cash inflows or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, forward currency contracts, options and swaps to help the ETF track its underlying index.

The Portfolio reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Portfolio employs a temporary defensive measure, the Portfolio may not achieve its investment objective. Periodically the Adviser will review the allocations for the Portfolio in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Portfolio in the underlying investment companies without notice to shareholders or the holders of the variable annuity or variable life insurance policies.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Portfolio, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Portfolio, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● The value of particular foreign equity securities which the Portfolio’s underlying investment companies may purchase or foreign stock markets on which the securities they may purchase are traded may decline in value.

● Stocks of large cap or small cap foreign companies in which the Portfolio’s underlying investment companies may invest may temporarily fall out of favor with investors or may be more volatile than particular foreign stock markets or foreign stock markets as a whole.

● The smaller the capitalization of a company, generally the less liquid its stock and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records and are more likely to fail than companies with larger market capitalizations.

● Stocks of large cap or small cap foreign companies in which the Portfolio’s underlying investment companies may invest may suffer unexpected losses or lower than expected earnings or such securities may become difficult or impossible to sell at the time and for the price the underlying investment advisers would like.

● Because the Portfolio owns shares of underlying investment companies that invest in foreign issuers, the Portfolio is subject to risks presented by investments in such issuers. Securities of foreign issuers may be negatively affected by political events, economic conditions, or inefficient, illiquid or unregulated markets in foreign countries. Foreign issuers may be subject to inadequate regulatory or accounting standards.

● Investments in emerging market securities by underlying investment companies in which the Portfolio invests are subject to higher risks than those in developed market countries because there is greater uncertainty in less established markets and economics. The foregoing risks may be greater in frontier markets, which are among the smallest and least mature investment markets.

● Currency risk is the risk that exchange rates for currencies in which securities held by the underlying investment companies in which the Portfolio invests are denominated will fluctuate daily. In general, the underlying investment companies do not hedge currency risk. As a result, if currencies in which foreign holdings are denominated depreciate against the U.S. Dollar, the value of your investment in the Portfolio may be adversely affected.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Portfolio could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Portfolio invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in equity securities of foreign companies, the NAV of the Portfolio will change with changes in the share prices of the investment companies in which the Portfolio invests.

● There is a risk that the Portfolio, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Portfolio will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. the Portfolio may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Cyber security risk is the risk of an unauthorized breach and access to Portfolio assets, Portfolio or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Portfolio, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Portfolio investors from purchasing, redeeming or exchanging shares or receiving distributions. The Portfolio and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Portfolio or its service providers may adversely impact and cause financial losses to the Portfolio or its shareholders.

More information about the Portfolio’s investments and risks is contained under the section entitled “More About Each Portfolio’s Investments and Risks.”

Risk Lose Money [Text]

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You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The chart below illustrates the performance of the Portfolio. The information shows you how the Portfolio’s performance has varied year by year and provides some indication of the risks of investing in the Portfolio. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

Performance Information Illustrates Variability of Returns [Text]

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The information shows you how the Portfolio's performance has varied year by year and provides some indication of the risks of investing in the Portfolio.

Performance Availability Phone [Text]

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(866) 780-0357 Ext. 3863

Performance Availability Website Address [Text]

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www.matsonmoney.com

Performance Past Does Not Indicate Future [Text]

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Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future.

Bar Chart [Heading]

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TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 9.78% (quarter ended December 31, 2019)

Worst Quarter: -14.64% (quarter ended December 31, 2018)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Explanation after Tax Higher

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In certain cases, the figure representing "Portfolio Returns After Taxes on Distributions and Sale of Portfolio Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

Performance Table Narrative

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The following table compares the average annual total returns of the Portfolio before and after taxes for the past calendar year, the past five calendar years, and since inception to the average total returns of a broad-based securities market index for the same periods.

Matson Money | Matson Money International Equity VI Portfolio | MSCI World (excluding U.S.) Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

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22.49%

5 Years

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5.42%

Since Inception

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4.51%

Inception Date

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Feb. 18, 2014

Matson Money | Matson Money International Equity VI Portfolio | Composite Index

Prospectus [Line Items]

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1 Year

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21.10%

^[1]

5 Years

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6.33%

^[1]

Since Inception

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5.20%

^[1]

Inception Date

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Feb. 18, 2014

^[1]

Matson Money | Matson Money International Equity VI Portfolio | Institutional Class

Prospectus [Line Items]

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Trading Symbol

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FMVIX

Management Fees

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0.50%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

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0.36%

Acquired fund fees and expenses

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0.43%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.29%

One Year

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$ 132

Three Years

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410

Five Years

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710

Ten Years

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$ 1,561

Annual Return 2015

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(3.74%)

Annual Return 2016

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7.70%

Annual Return 2017

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27.18%

Annual Return 2018

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(19.31%)

Annual Return 2019

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17.36%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Dec. 31, 2019

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

9.78%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.64%)

1 Year

rr_AverageAnnualReturnYear01

17.36%

5 Years

rr_AverageAnnualReturnYear05

4.54%

Since Inception

rr_AverageAnnualReturnSinceInception

2.53%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

Matson Money | Matson Money International Equity VI Portfolio | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

16.30%

^[3]

5 Years

rr_AverageAnnualReturnYear05

3.72%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

1.80%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

^[3]

Matson Money | Matson Money International Equity VI Portfolio | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

11.27%

^[4]

5 Years

rr_AverageAnnualReturnYear05

3.45%

^[4]

Since Inception

rr_AverageAnnualReturnSinceInception

1.89%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

^[4]

[1] The Composite Index is comprised of the MSCI EAFE Index, MSCI EAFE Value Index, MSCI EAFE Small Cap Index, and MSCI Emerging Markets Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Portfolio's Investments and Risks."

[2] Acquired Fund Fees and Expenses are indirect fees and expenses that the Portfolio incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Portfolio Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

[4] In certain cases, the figure representing "Portfolio Returns After Taxes on Distributions and Sale of Portfolio Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Matson Money | Free Market Fixed Income Fund

Prospectus [Line Items]

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Risk/Return [Heading]

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FREE MARKET FIXED INCOME FUND FMFIX

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Free Market Fixed Income Fund (for this section only, the “Fund”) seeks total return (consisting of current income and capital appreciation).

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual fund Operating Expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 3% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

3.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in fixed income securities that the Adviser believes offer the prospect of providing total return, or invest substantially all of their assets in such fixed income securities. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Fund’s net assets to be invested in the securities of investment companies that invest in the types of securities described in each asset class below, with less than 2% of the net assets invested in cash or money market instruments.

One-Year Fixed Income Asset Class: The underlying investment companies generally will purchase U.S. government obligations, U.S. government agency obligations, dollar-denominated obligations of foreign issuers issued in the U.S., securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the U.S.; foreign government and agency obligations, bank obligations, including the obligations of U.S. subsidiaries and branches of foreign banks, corporate obligations, commercial paper, repurchase agreements, and obligations of supranational organizations such as the World Bank, the European Investment Bank, and the Inter-American Development Bank. Generally, obligations comprising this asset class will mature within one year from the date of settlement, but substantial investments may be made in obligations maturing within two years from the date of settlement when greater returns are available.

Two-Year Global Fixed Income Asset Class: The underlying investment companies generally will purchase obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, corporate debt obligations, bank obligations, commercial paper, repurchase agreements, and other debt obligations of domestic and foreign issuers with maturities of no more than two years. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the underlying investment adviser(s) will focus investment in the longer-term area, otherwise, the underlying investment companies will focus investment in the shorter-term area of the eligible maturity range. Because many of the investments of the underlying investment companies in this asset class will be denominated in foreign currencies, the underlying investment companies may also enter into foreign currency forward contracts to attempt to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another.

Intermediate Government Fixed Income Asset Class: The underlying investment companies generally will purchase debt obligations of the U.S. government and U.S. government agencies. Generally, investment companies in the asset class will purchase securities with maturities of between five and fifteen years, however such investment companies ordinarily will have an average weighted maturity of between three and ten years. The underlying investment companies may invest a portion of their assets in the obligations of foreign governments. Those obligations at the time of purchase must be either rated in the highest rating category of a nationally recognized statistical rating organization or, in the case of any obligation that is unrated, of comparable quality.

Five-Year Global Fixed Income Asset Class: The underlying investment companies generally will purchase obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, corporate debt obligations, bank obligations, commercial paper, repurchase agreements, obligations of other domestic and foreign issuers, securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the United States, and obligations of supranational organizations. Generally, obligations comprising this asset class have a weighted average maturity not exceeding five years. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the underlying investment adviser(s) will focus investment in the longer-term area, otherwise, the underlying investment companies will focus investment in the shorter-term area of the eligible maturity range. Because many of the investments of the underlying investment companies in this asset class will be denominated in foreign currencies, the underlying investment companies may also enter into foreign currency forward contracts to attempt to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another.

Short-Term Corporate Bond Asset Class: The underlying investment companies generally will track the investment results of the ICE BofAML 1-5 Year US Corporate Index, which measures the performance of investment-grade corporate bonds of both U.S. and non- U.S. issuers that are U.S. dollar denominated and publicly issued in the U.S. domestic market and have a remaining maturity of greater than or equal to one year and less than five years.

Intermediate-Term Corporate Bond Asset Class: The underlying investment companies generally will track the investment results of the ICE BofAML 5-10 Year US Corporate Index, which measures the performance of investment-grade corporate bonds of both U.S. and non-U.S. issuers that are U.S. dollar denominated and publicly issued in the U.S. domestic market and have a remaining maturity of greater than or equal to five years and less than ten years.

Inflation Protected Securities Asset Class: The underlying investment companies generally will track the investment results of the Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L), which measures the performance of the inflation-protected public obligations of the U.S. Treasury, commonly known as “TIPS.” TIPS are securities issued by the U.S. Treasury that are designed to provide inflation protection to investors. TIPS are income-generating instruments whose interest and principal payments are adjusted for inflation - a sustained increase in prices that erodes the purchasing power of money. The inflation adjustment, which is typically applied monthly to the principal of the bond, follows a designated inflation index, the consumer price index (“CPI”), and TIPS’ principal payments are adjusted according to changes in the CPI. A fixed coupon rate is applied to the inflation-adjusted principal so that as inflation rises, both the principal value and the interest payments increase.

The underlying investment companies may also use derivatives, such as futures contracts and options on futures contracts for equity securities and indices, to hedge currency exposure or to adjust market exposure based on actual or expected cash inflows or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, forward currency contracts, options and swaps to help the ETF track its underlying index.

Certain underlying investment companies may concentrate their investments (invest more than 25% of its total assets) in obligations of U.S. and foreign banks and bank holding companies when the yield to maturity on eligible portfolio investments in banking securities as a group generally exceeds the yield to maturity on all other eligible portfolio investments as a group generally for a period of five consecutive days when the New York Stock Exchange is open for trading. While the Fund will not concentrate its investments in any one industry, the Fund may be focused on banking sectors under certain circumstances.

The Fund reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Fund employs a temporary defensive measure, the Fund may not achieve its investment objective. Periodically the Adviser will review the allocations for the Fund in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Fund in the underlying investment companies without notice to shareholders.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Fixed income securities in which the Fund’s underlying investment companies may invest are subject to certain risks, including: interest rate risk, reinvestment risk, prepayment and extension risk, credit/default risk, and the risks associated with investing in repurchase agreements.

● Interest rate risk involves the risk that prices of fixed income securities will rise and fall in response to interest rate changes.

● Reinvestment risk involves the risk that proceeds from matured investments may be re-invested at lower interest rates.

● Prepayment risk involves the risk that in declining interest rates environments prepayments of principal could increase and require the Fund to reinvest proceeds of the prepayments at lower interest rates.

● Extension risk involves the risk that prepayments of principal will decrease when interest rates rise resulting in a longer effective maturity of a security.

● Credit risk is the risk that the issuer of a security may be unable to make interest payments and/or repay principal when due. Credit risk also involves the risk that the credit rating of a security may be lowered.

● Repurchase agreement risk involves the risk that the other party to a repurchase agreement will be unable to complete the transaction and the underlying investment company in which the Fund invests may suffer a loss as a result.

● Because the Fund owns shares of underlying investment companies that invest in foreign issuers, the Fund is subject to risks presented by investments in such issuers. Securities of foreign issuers may be negatively affected by political events, economic conditions, or inefficient, illiquid or unregulated markets in foreign countries. Foreign issuers may be subject to inadequate regulatory or accounting standards.

● Currency risk is the risk that exchange rates for currencies in which securities held by the underlying investment companies in which the Fund invests are denominated will fluctuate daily. Forward foreign currency exchange contracts may limit potential gains from a favorable change in value between the U.S. dollar and foreign currencies. Unanticipated changes in currency pricing may result in poorer overall performance for the Fund than if it had not engaged in these contracts.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Inflation protected securities, such as TIPS, generally will fluctuate in response to changes in real interest rates, generally decreasing when real interest rates rise and increasing when real interest rates fall. In addition, interest payments on inflation-protected securities will generally vary up or down along with the rate of inflation. Real interest rates are generally measured as a nominal interest less an inflation rate. As such, investors should be aware that an investment in TIPS over a particular timeframe may decrease in value even in an inflationary environment. There can be no assurance that the inflation index used will accurately measure the real rate of inflation in the prices of goods and services. Because of their inflation adjustment feature, inflation-protected bonds typically have lower yields than conventional fixed-rate bonds.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Fund could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Fund invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in fixed income securities, the NAV of the Fund will change with changes in the share prices of the investment companies in which the Fund invests.

● Not all obligations of U.S. government agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some are backed only by the credit of the issuing agency or instrumentality. Accordingly, there may be some risk of default by the issuer in such cases.

● There is a risk that the Fund, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Fund will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● Banks are very sensitive to changes in money market and general economic conditions. Adverse general economic conditions can cause financial difficulties for a bank’s borrowers and the borrowers’ failure to repay their loans can adversely affect the bank’s financial situation. Banks are subject to extensive regulation and decisions by regulators may limit the loans banks make and the interest rates and fees they charge, which could reduce bank profitability.

● Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

More information about the Fund’s investments and risks is contained under the section entitled “More About Each Fund’s Investments and Risks.”

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The chart below illustrates the long-term performance of the Fund. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

(866) 780-0357 Ext. 3863

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.matsonmoney.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

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TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 1.99% (quarter ended March 31, 2019)

Worst Quarter: -1.44% (quarter ended June 30, 2013)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns of the Fund before and after taxes for the past calendar year, the past five calendar years, and past ten calendar years to the average total returns of a broad-based securities market index for the same periods.

Matson Money | Free Market Fixed Income Fund | FTSE World Government Bond Index 1-5 Years(reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

3.86%

5 Years

rr_AverageAnnualReturnYear05

1.92%

10 Years

rr_AverageAnnualReturnYear10

1.85%

Matson Money | Free Market Fixed Income Fund | Composite Index

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

5.34%

^[1]

5 Years

rr_AverageAnnualReturnYear05

2.04%

^[1]

10 Years

rr_AverageAnnualReturnYear10

2.17%

^[1]

Matson Money | Free Market Fixed Income Fund | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

FMFIX

Management Fees

rr_ManagementFeesOverAssets

0.49%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.06%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.12%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.67%

One Year

rr_ExpenseExampleYear01

$ 68

Three Years

rr_ExpenseExampleYear03

214

Five Years

rr_ExpenseExampleYear05

373

Ten Years

rr_ExpenseExampleYear10

$ 833

Annual Return 2010

rr_AnnualReturn2010

2.93%

Annual Return 2011

rr_AnnualReturn2011

2.84%

Annual Return 2012

rr_AnnualReturn2012

2.02%

Annual Return 2013

rr_AnnualReturn2013

(1.43%)

Annual Return 2014

rr_AnnualReturn2014

1.11%

Annual Return 2015

rr_AnnualReturn2015

0.19%

Annual Return 2016

rr_AnnualReturn2016

1.30%

Annual Return 2017

rr_AnnualReturn2017

1.05%

Annual Return 2018

rr_AnnualReturn2018

0.66%

Annual Return 2019

rr_AnnualReturn2019

4.78%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2019

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.99%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2013

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(1.44%)

1 Year

rr_AverageAnnualReturnYear01

4.78%

5 Years

rr_AverageAnnualReturnYear05

1.58%

10 Years

rr_AverageAnnualReturnYear10

1.53%

Matson Money | Free Market Fixed Income Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

4.17%

^[3]

5 Years

rr_AverageAnnualReturnYear05

1.06%

^[3]

10 Years

rr_AverageAnnualReturnYear10

1.04%

^[3]

Matson Money | Free Market Fixed Income Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

2.83%

5 Years

rr_AverageAnnualReturnYear05

0.99%

10 Years

rr_AverageAnnualReturnYear10

0.99%

[1] The Composite Index is comprised of the Three-Month Treasury Bill Index, Bloomberg Barclays Intermediate Government Bond Index, ICE BofAML 1-3 Year US Government/Corporate Index and Bloomberg Barclays U.S. Aggregate Bond Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled " More About Each Fund's Investments and Risks."

[2] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Document Period End Date	dei_DocumentPeriodEndDate	Aug. 31, 2019
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Document Effective Date	dei_DocumentEffectiveDate	Feb. 28, 2020
Prospectus Date	rr_ProspectusDate	Feb. 28, 2020

XML

Total

Institutional Class Prospectus | Boston Partners Emerging Markets Fund

SUMMARY SECTION — BOSTON PARTNERS EMERGING MARKETS FUND

Investment Objective

The Fund seeks long-term growth of capital.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners Emerging Markets Fund Institutional Class
Management Fees	0.85%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	2.04%
Acquired fund fees and expenses	0.04%	[1]
Total Annual Fund Operating Expenses	2.93%
Fee Waivers and/or Expense Reimbursements	(1.83%)	[2]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	1.10%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | Boston Partners Emerging Markets Fund | Institutional Class | USD ($)	1,121	7,337	13,812	31,210

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal period ended August 31, 2019, the portfolio turnover rate for the Fund was 155% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund will pursue its objective through a value oriented, research-driven strategy of investing in equity securities and financial instruments with equity like characteristics designed to provide exposure to emerging markets. Securities are selected by the Adviser using its "three circles" approach which combines a quantitative screening with a fundamental bottom up selection process. This investment strategy is grounded in the following principles: (1) low valuation stocks outperform high valuation stocks; (2) companies with strong fundamentals, e.g. high and sustainable returns on invested capital, outperform companies with weak fundamentals; and (3) stocks with positive business momentum, e.g. rising earnings estimates, outperform stocks with negative business momentum. The Adviser examines various factors in determining the value characteristics of issuers, including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals, such as return-on-equity and earnings growth and cash flow.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in the securities of emerging market issuers, related derivative instruments and other investments that are tied economically to emerging market countries. The Adviser considers an emerging market country to include any country that is: 1) generally recognized to be an emerging market country by the international financial community, including the World Bank; 2) classified by the United Nations as a developing country; or 3) included in the MSCI Emerging Markets Index. Due to the unique relationship between China and its separately administered regions, the Adviser includes Hong Kong and Macau as emerging markets, independent of above definitions 1 through 3. The Adviser determines that an investment is tied economically to an emerging market if such investment satisfies one or more of the following conditions: 1) the issuer’s primary trading market is in an emerging market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in emerging markets; 3) the investment is included in an index representative of emerging markets; and 4) the investment is exposed to the economic risks and returns of emerging markets.

In managing the Fund’s portfolio, the Adviser will seek to identify mispriced publicly traded equity securities of emerging market companies and purchase securities that the Adviser believes will outperform, emphasizing low valuation, positive business momentum and high quality.

The Fund’s portfolio is rebalanced regularly to maintain the optimal risk/return trade-off. The Adviser assesses each stock’s changing characteristics relative to its contribution to portfolio risk. The Adviser will sell a stock that the Adviser believes no longer offers an appropriate return-to-risk tradeoff. The Fund’s investment adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

The equity securities in which the Fund will invest, which may include equity securities of non-U.S. issuers that are traded in the markets of the United States, include equity securities issued by large-, mid- and small- or micro-cap companies, as well as exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers").

The Fund may invest up to 20% of its net assets in high yield debt obligations (commonly known as “junk bonds”), such as bonds and debentures, used by corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Junk bonds are rated BB or lower by S&P Global, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded. The Fund will primarily invest in fixed income instruments, including high yield debt obligations, when the Fund believes that such instruments offer a better risk/reward profile than comparable equity opportunities.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund’s investments will be spread over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest in exchange traded funds to the extent permitted by the Investment Company Act of 1940, as amended (“1940 Act”), and applicable SEC orders.

The Fund may participate as a purchaser in initial public offerings of securities (“IPOs”). An IPO is a company’s first offering of stock to the public.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may also seek to increase its income by lending portfolio securities.

The Fund will invest in derivatives, including put and call options, futures, contracts for differences, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes. Contracts for differences offer exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin. The Fund’s investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, contracts for differences, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Equity Securities Risk. The Fund may invest in, or have exposure to, equity securities. Equity securities tend to be more volatile than other investment choices, such as debt and money market instruments. The value of your investment may decrease in response to overall stock market movements or the value of individual securities.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in Junk Bonds, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such Junk Bonds are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium-capitalization stocks.

● Limited Operating History Risk: The Fund has a limited operating history upon which prospective investors can evaluate its performance. Although the investment strategies described herein may have been utilized by investment accounts managed by the Adviser’s investment team, past performance is not indicative of future results.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund makes may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

● Portfolio Turnover Risk. The Fund may frequently trade its portfolio securities, resulting in higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Segregated Account Risk. The Fund’s transactions in derivative instruments may require the Fund to establish a segregated account consisting of cash or liquid securities in an amount sufficient to cover the transactions. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund’s assets could impede portfolio management or the Fund’s ability to meet redemption requests or other current obligations.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Performance Information

The bar chart and table below illustrate the performance of the Boston Partners Emerging Markets Fund's Institutional Class. The bar chart below shows you the performance of the Fund’s Institutional Class for one year. This also provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Year Ended December 31

Best and Worst Quarterly Performance (for the period reflected in the chart above):

Best Quarter:	13.92% (quarter ended March 31, 2019)
Worst Quarter:	-11.07% (quarter ended December 31, 2018)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Average Annual Total Returns - Institutional Class Prospectus - Boston Partners Emerging Markets Fund		1 Year	Since Inception	Inception Date
Institutional Class		28.29%	2.57%	Oct. 17, 2017
Institutional Class | After Taxes on Distributions	[1]	26.50%	1.84%	Oct. 17, 2017
Institutional Class | After Taxes on Distributions and Sales		17.42%	1.81%	Oct. 17, 2017
MSCI Emerging Markets Index - Net Return (reflects no deduction for fees, expenses or taxes)	[2]	18.42%	1.98%	Oct. 17, 2017
MSCI Emerging Markets Index - Gross Return (reflects no deduction for fees, expenses or taxes)	[2]	18.88%	2.37%	Oct. 17, 2017

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.10% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] Effective August 31, 2019, the Fund changed its primary index from the MSCI Emerging Markets Index - Gross Return to the MSCI Emerging Markets Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

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Investor Class Prospectus | Boston Partners Small Cap Value Fund II

SUMMARY SECTION — BOSTON PARTNERS SMALL CAP VALUE FUND II

Investment Objective

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Class Prospectus Boston Partners Small Cap Value Fund II Investor Class
Management Fees	0.95%	[1]
Distribution and/or Service (12b-1) Fees	0.25%
Other Expenses	0.21%
Acquired fund fees and expenses	0.01%	[2]
Total Annual Fund Operating Expenses	1.42%
Fee Waivers and/or Expense Reimbursements	(0.07%)	[3]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	1.35%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Investor Class Prospectus | Boston Partners Small Cap Value Fund II | Investor Class | USD ($)	138	390	662	1,440

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 29% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers with small market capitalizations and identified by the Adviser as having value characteristics. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Value Index. The Russell 2000^® Value Index is an unmanaged index that contains stocks from the Russell 2000^® Index with less than average growth orientation. As of November 30, 2019, the median market capitalization of this index was $666 million and the largest stock was $6.7 billion. Please note that this range is as of a particular point in time and is subject to change.

The Fund generally invests in the equity securities of small companies. The Adviser will seek to invest in companies it considers to be well managed and to have attractive fundamental financial characteristics. The Adviser believes greater potential for price appreciation exists among small companies since they tend to be less widely followed by other securities analysts and thus may be more likely to be undervalued by the market. The Fund may invest from time to time a portion of its assets, not to exceed 20% (under normal conditions) at the time of purchase, in companies with larger market capitalizations.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may also invest up to 25% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Small Cap Companies Risk. The Fund will invest in smaller issuers which are more volatile and less liquid than investments in issuers with a market capitalization greater than the market capitalization of companies in the Russell 2000^® Value Index. Small market capitalization issuers are not as diversified in their business activities as issuers with market capitalizations greater than the market capitalization of companies in the Russell 2000^® Value Index and are more susceptible to changes in the business cycle.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Small Cap Value Fund II’s Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	14.79% (quarter ended December 31, 2010)
Worst Quarter:	-20.47% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Investor Class Prospectus - Boston Partners Small Cap Value Fund II		1 Year	5 Years	10 Years
Investor Class		27.71%	6.96%	10.56%
Investor Class | After Taxes on Distributions	[1]	27.01%	5.89%	9.94%
Investor Class | After Taxes on Distributions and Sales		16.86%	5.27%	8.64%
Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)		22.39%	6.99%	10.56%

[1] Prior to October 1, 2019, the management fee was 1.00%.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.35% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.35%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time, the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.35% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Institutional Class Prospectus | Boston Partners Global Long/Short Fund

SUMMARY SECTION — BOSTON PARTNERS GLOBAL LONG/SHORT FUND

Investment Objective

The Fund seeks long-term growth of capital.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners Global Long/Short Fund Institutional Class
Management Fees	1.50%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.14%
Dividend expense on short sales	0.83%
Interest expense on borrowings	none
Acquired fund fees and expenses	0.01%	[1]
Total Annual Fund Operating Expenses	2.48%	[2]

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and Fund operating expenses remain the same. Although your actual costs and returns might be different, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | Boston Partners Global Long/Short Fund | Institutional Class | USD ($)	2,511	7,725	13,205	28,160

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 99% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage. The Fund invests, both long and short, in securities issued by U.S. and non-U.S. companies of any capitalization size.

With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, including return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund's portfolio is rebalanced regularly. The Adviser assesses each investment's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell an investment held long or close out a short position that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

Under normal circumstances, the Adviser expects to sell securities short so that the Fund's portfolio is approximately 50% net long with an average of between 30% and 70% net long.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry. The Fund is non-diversified, and may invest in fewer securities at any one time than a diversified fund.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by U.S. and foreign corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by S&P Global, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

● Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Global Long/Short Fund's Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	4.10% (quarter ended June 30, 2015)
Worst Quarter:	-7.66% (quarter ended December 31, 2018)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Average Annual Total Returns - Institutional Class Prospectus - Boston Partners Global Long/Short Fund		1 Year	5 Years	Since Inception	Inception Date
Institutional Class		4.59%	2.18%	2.05%	Dec. 31, 2013
Institutional Class | After Taxes on Distributions	[1]	4.27%	1.99%	1.89%	Dec. 31, 2013
Institutional Class | After Taxes on Distributions and Sales		2.95%	1.67%	1.58%	Dec. 31, 2013
MSCI® World Index - Net Return (reflects no deduction for fees, expenses or taxes)	[2]	27.67%	8.74%	8.10%	Dec. 31, 2013
MSCI® World Index - Gross Return (reflects no deduction for fees, expenses or taxes)	[2]	28.40%	9.36%	8.70%	Dec. 31, 2013

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 2.00% of the average daily net assets attributable to the Fund's Institutional Class shares. Because dividend expenses on short sales, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and/or expense reimbursements) are expected to exceed 2.00%. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 2.00% or the expense cap then in effect, or whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

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Institutional Class Prospectus | Boston Partners Long/Short Equity Fund

SUMMARY SECTION — BOSTON PARTNERS LONG/SHORT EQUITY FUND

Investment Objective

The Fund seeks long-term capital appreciation while reducing exposure to general equity market risk. The Fund seeks a total return greater than that of the S&P 500^® Index over a full market cycle.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners Long/Short Equity Fund Institutional Class
Management Fees	2.25%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.21%
Dividend expense on short sales	0.22%
Interest expense on borrowings	none
Total Annual Fund Operating Expenses	2.68%
Fee Waivers and/or Expense Reimbursements	(0.50%)	[1]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	2.18%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | Boston Partners Long/Short Equity Fund | Institutional Class | USD ($)	2,211	7,850	13,755	29,757

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 64% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage. The Fund invests, both long and short, in securities principally traded in the United States markets. The Fund may invest in securities of companies operating for three years or less (“unseasoned issuers”). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the United States equity market generally. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities. Under normal circumstances, the Adviser expects that the Fund’s long positions will not exceed approximately 125% of the Fund’s net assets.

The Fund’s long and short positions may involve (without limit) equity securities of foreign issuers that are traded in the markets of the United States. The Fund may also invest up to 20% of its total assets directly in equity securities of foreign issuers.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations. High yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund’s assets could impede portfolio management or the Fund’s ability to meet redemption requests or other current obligations.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Equity Fund’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	13.47% (quarter ended December 31, 2010)
Worst Quarter:	-9.97% (quarter ended June 30, 2010)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods. Although the Fund compares its average total return to a broad-based securities market index, the Fund seeks returns that are not correlated to securities market returns. The Fund seeks to achieve a 12-15% return over a full market cycle; however, there can be no guarantee that such returns will be achieved.

Average Annual Total Returns - Institutional Class Prospectus - Boston Partners Long/Short Equity Fund		1 Year	5 Years	10 Years
Institutional Class		9.12%	2.80%	6.93%
Institutional Class | After Taxes on Distributions	[1]	6.69%	1.50%	5.21%
Institutional Class | After Taxes on Distributions and Sales		7.10%	2.10%	5.28%
S&P 500® Index (reflects no deduction for fees, expenses or taxes)		31.49%	11.70%	13.56%

[1] Effective February 28, 2020, the Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class exceeds 1.96% of the average daily net assets attributable to the Fund's Institutional Class shares. Because dividend expenses on short sales, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 1.96%. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.96% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement. Prior to February 28, 2020, the Fund's Institutional Class fee cap was 2.50%.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

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Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund

SUMMARY SECTION — WPG PARTNERS SMALL/MICRO CAP VALUE FUND

Investment Objective

The Fund seeks capital appreciation by investing primarily in common stocks, securities convertible into common stocks and in special situations.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus WPG Partners Small/Micro Cap Value Fund Institutional Class
Management Fees	0.80%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.43%
Total Annual Fund Operating Expenses	1.23%
Fee Waivers and/or Expense Reimbursements	(0.13%)	[1]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	1.10%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund | Institutional Class | USD ($)	1,121	3,775	6,632	14,772

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 79% of the average value of its portfolio.

Summary of Principal Investment Strategies

Currently, the Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in equity securities of U.S. companies that, at the time of purchase, have a market capitalization that is within the range of the market capitalization of issuers in the Russell 2000^® Value Index. As of November 30, 2019, the median market capitalization of the companies in the Russell 2000^® Value Index is $666 million and the largest stock is $6.7 billion. The Fund may invest in depositary receipts and equity securities of foreign companies. Although the Fund invests primarily in common stocks, the Fund may invest in all types of equity and equity-related securities, including (without limitation):

● Securities convertible into common stocks.

● Shares of real estate investment trusts (“REITs”).

● Warrants and rights to purchase common stocks.

● Preferred stocks.

● Exchange-traded limited partnerships.

Special Situations: The Fund may invest in companies that may experience unusual and possibly unique developments which may create a special opportunity for significant returns. Special situations include: significant technological improvements or important discoveries; reorganizations, recapitalizations or mergers; favorable resolutions of litigation; new management or material changes in company policies; and actual or potential changes in control of a company.

Strategies: The Adviser uses a value approach to select the Fund’s investments. Using this investment style, the Adviser seeks securities selling at substantial discounts to their underlying values and then holds these securities until the market values reflect what the Adviser believes to be their intrinsic values. The Adviser employs a bottom-up strategy, focusing on undervalued industries that the Adviser believes are experiencing positive change. The Adviser then uses both qualitative and quantitative methods to assess a security’s potential value. The portfolio managers managing the Fund meet with a multitude of companies annually to identify companies with increasing returns on capital in their core businesses which are selling at attractive valuations.

Factors the Adviser looks for in selecting investments include (without limitation):

● Increasing returns on invested capital.

● Companies who have demonstrated an ability to generate high return on invested capital (ROIC).

● Companies which provide solid cash flows with appropriate capital.

● Potential catalysts such as new products, cyclical upturns and changes in management.

● Low market valuations relative to earnings forecast, book value, cash flow and sales.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Rights and Warrants Risk. The purchase of rights or warrants involves the risk that the Fund could lose the purchase value of a right or warrant if the right to subscribe to additional shares is not executed prior to the right’s or warrant’s expiration. Also, the purchase of rights and/or warrants involves the risk that the effective price paid for the right and/or warrant added to the subscription price of the related security may exceed the value of the subscribed security’s market price such as when there is no movement in the level of the underlying security.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

● Special Situations Risk. The Fund will seek to benefit from “special situations,” such as mergers, reorganizations, or other unusual events expected to affect a particular issuer. There is a risk that the “special situation” might not occur or involve longer time frames than originally expected, which could have a negative impact on the price of the issuer’s securities and fail to produce gains or produce a loss for the Fund.

Performance Information

The bar chart and table below illustrate the long-term performance of the WPG Partners Small/Micro Cap Value Fund’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	15.93% (quarter ended March 31, 2012)
Worst Quarter:	-25.00% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Institutional Class Prospectus - WPG Partners Small/Micro Cap Value Fund		1 Year	5 Years	10 Years
Institutional Class		23.35%	1.03%	6.99%
Institutional Class | After Taxes on Distributions	[1]	23.14%	(0.14%)	5.69%
Institutional Class | After Taxes on Distributions and Sales		13.83%	0.42%	5.30%
Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)		22.39%	6.99%	10.56%

[1] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time, the Fund's total annual fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.10% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In certain cases, the figure representing "Returns After Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

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RBB FUND, INC.

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Investor Class Prospectus | Boston Partners Global Long/Short Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

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SUMMARY SECTION — BOSTON PARTNERS GLOBAL LONG/SHORT FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The Fund seeks long-term growth of capital.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

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February 28, 2021

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 99% of the average value of its portfolio.

Portfolio Turnover, Rate

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99.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

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Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and Fund operating expenses remain the same. Although your actual costs and returns might be different, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage The Fund invests, both long and short, in securities issued by U.S. and non-U.S. companies of any capitalization size.

With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, including return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund's portfolio is rebalanced regularly. The Adviser assesses each investment's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell an investment held long or close out a short position that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

Under normal circumstances, the Adviser expects to sell securities short so that the Fund's portfolio is approximately 50% net long with an average of between 30% and 70% net long.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry. The Fund is non-diversified and may invest in fewer securities at any one time than a diversified fund.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by U.S. and foreign corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by S&P Global, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objectives. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the long-term performance of the Boston Partners Global Long/Short Fund's Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year to year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Investor Class has varied year to year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	4.01% (quarter ended June 30, 2015)
Worst Quarter:	-7.65% (quarter ended December 31, 2018)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Investor Class Prospectus | Boston Partners Global Long/Short Fund | MSCI World Index - Net Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

27.67%

^[1]

5 Years

rr_AverageAnnualReturnYear05

8.74%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

8.66%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 11, 2014

^[1]

Investor Class Prospectus | Boston Partners Global Long/Short Fund | MSCI World Index - Gross Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

28.40%

^[1]

5 Years

rr_AverageAnnualReturnYear05

9.36%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

9.26%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 11, 2014

^[1]

Investor Class Prospectus | Boston Partners Global Long/Short Fund | Investor Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

BGRSX

Management Fees

rr_ManagementFeesOverAssets

1.50%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.14%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.73%

^[3]

One Year

rr_ExpenseExampleYear01

$ 276

Three Years

rr_ExpenseExampleYear03

798

Five Years

rr_ExpenseExampleYear05

1,346

Ten Years

rr_ExpenseExampleYear10

$ 2,841

Annual Return 2015

rr_AnnualReturn2015

6.26%

Annual Return 2016

rr_AnnualReturn2016

2.09%

Annual Return 2017

rr_AnnualReturn2017

7.23%

Annual Return 2018

rr_AnnualReturn2018

(9.38%)

Annual Return 2019

rr_AnnualReturn2019

4.27%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2015

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

4.01%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(7.65%)

1 Year

rr_AverageAnnualReturnYear01

4.27%

5 Years

rr_AverageAnnualReturnYear05

1.91%

Since Inception

rr_AverageAnnualReturnSinceInception

2.15%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 11, 2014

Investor Class Prospectus | Boston Partners Global Long/Short Fund | Investor Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

4.03%

^[4]

5 Years

rr_AverageAnnualReturnYear05

1.74%

^[4]

Since Inception

rr_AverageAnnualReturnSinceInception

2.00%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 11, 2014

^[4]

Investor Class Prospectus | Boston Partners Global Long/Short Fund | Investor Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

2.69%

5 Years

rr_AverageAnnualReturnYear05

1.46%

Since Inception

rr_AverageAnnualReturnSinceInception

1.65%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 11, 2014

[1] Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Investor Class shares exceeds 2.25% of the average daily net assets attributable to the Fund's Investor Class shares. Because dividend expenses on short sales, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and/or expense reimbursements) are expected to exceed 2.25%. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 2.25% or the expense cap then in effect, or whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Investor Class Prospectus | Boston Partners Long/Short Research Fund

Prospectus [Line Items]

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Risk/Return [Heading]

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SUMMARY SECTION — BOSTON PARTNERS LONG/SHORT RESEARCH FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term total return.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 60% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

60.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund uses a hedged strategy. The Fund actively invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales (i.e. sales of securities the Fund does not own) are invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage.

The Fund invests, both long and short, in equity securities issued by large-, mid- and small (or “micro”)-cap companies, as well as other instruments that are convertible into equity securities. Equity securities in which the Fund may invest include exchange-traded and over-the-counter common and preferred stocks, warrants, rights, convertible securities, depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies and real estate investment trusts (“REITs”), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less (“unseasoned issuers”). The Fund may also invest in depository receipts and equity securities of foreign companies (denominated in either U.S. dollars or foreign currencies), put and call options, futures, indexed securities and fixed-income securities (including bonds, notes, asset-backed securities, convertible securities, Eurodollar and Yankee dollar instruments, preferred stocks and money market instruments) and high yield securities (commonly referred to as “junk bonds”). Fixed income securities in which the Fund invests include those rated between AAA and D by a nationally recognized statistical rating organization (“NRSRO”), or deemed of comparable quality by the Adviser. The Adviser may also temporarily invest uninvested cash in money market funds and similar collective investment vehicles. The Fund may also seek to increase its income by lending portfolio securities.

The Adviser determines the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the U.S. equity market by investing less than 100% of its assets in net long positions. Selection of individual securities to be held long or sold short will be based on a mix of quantitative techniques and fundamental security analysis. The Adviser selects stocks on the basis of three criteria: value, fundamental business strength and momentum. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

Although the Fund seeks to follow a hedged strategy, there can be no assurance that the Fund’s portfolio or investments will be insulated from market moves or effectively hedged against risk.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest in exchange-traded funds to the extent permitted by the Investment Company Act of 1940, as amended (“1940 Act”), and applicable SEC orders.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The principal derivative instruments in which the Fund invests are futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps. The Fund’s investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Exchange-Traded Fund Risk. Exchange-traded funds (“ETFs”) are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an Adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations (of any rating, including defaulted securities and unrated securities), including bonds and debentures, issued by corporations and business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. Less liquid securities that the fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● Indexed Securities Risk. The Fund may invest in indexed securities whose value is linked to securities indices. Most such securities have values that rise and fall according to the change in one or more specified indices and may have characteristics similar to direct investments in the underlying securities. Depending on the index, such securities may have greater volatility than the market as a whole.

● Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may be incorrect in the stocks it buys and believes to be undervalued and in stocks it sells short and believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 300%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund’s obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales “against the box” may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not “against the box” involve a form of investment leverage, and the amount of the Fund’s loss on a short sale is potentially unlimited.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Research Fund’s Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year to year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073. 

Performance Information Illustrates Variability of Returns [Text]

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The bar chart below shows you how the performance of the Fund's Investor Class has varied year to year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	8.29% (quarter ended December 31, 2011)
Worst Quarter:	-9.91% (quarter ended September 30, 2011)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund’s Investor Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of a broad-based securities market index for the same periods.

Investor Class Prospectus | Boston Partners Long/Short Research Fund | S&P 500® Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

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31.49%

5 Years

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11.70%

Since Inception

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13.99%

Inception Date

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Nov. 29, 2010

Investor Class Prospectus | Boston Partners Long/Short Research Fund | Investor Class

Prospectus [Line Items]

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Trading Symbol

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BPRRX

Management Fees

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1.25%

Distribution and/or Service (12b-1) Fees

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0.25%

Other Expenses

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0.13%

Total Annual Fund Operating Expenses

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2.40%

^[1]

One Year

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$ 243

Three Years

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698

Five Years

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1,180

Ten Years

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$ 2,508

Annual Return 2011

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3.12%

Annual Return 2012

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13.13%

Annual Return 2013

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17.45%

Annual Return 2014

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6.86%

Annual Return 2015

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1.27%

Annual Return 2016

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3.40%

Annual Return 2017

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9.80%

Annual Return 2018

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(10.80%)

Annual Return 2019

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12.28%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Dec. 31, 2011

Highest Quarterly Return

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8.29%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Sep. 30, 2011

Lowest Quarterly Return

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(9.91%)

1 Year

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12.28%

5 Years

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2.86%

Since Inception

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6.24%

Inception Date

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Nov. 29, 2010

Investor Class Prospectus | Boston Partners Long/Short Research Fund | Investor Class | After Taxes on Distributions

Prospectus [Line Items]

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1 Year

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11.73%

^[2]

5 Years

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2.32%

^[2]

Since Inception

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5.85%

^[2]

Inception Date

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Nov. 29, 2010

^[2]

Investor Class Prospectus | Boston Partners Long/Short Research Fund | Investor Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

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1 Year

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7.65%

5 Years

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2.17%

Since Inception

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4.98%

Inception Date

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Nov. 29, 2010

[1] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to forgo all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total Annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) exceeds 1.75% of the average daily net assets attributable to the Fund's Investor Class shares. Because short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total Annual Fund Operating Expenses (after fee waivers and expense reimbursements) are expected to exceed 1.75%.This contractual limitation is in effect until at least February 28, 2021 and may not be terminated without Board approval. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.75% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Summit Global Investments | SGI U.S. Large Cap Equity Fund

SUMMARY SECTIONS     U.S. Large Cap Equity Fund

Investment Objective

The SGI U.S. Large Cap Equity Fund (for this section only, the “Fund”) seeks to outperform the S&P 500^® Index over a market cycle while reducing overall volatility. There can be no guarantee that the Fund will achieve its investment objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information — Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information — Reducing or Eliminating the Front-End Sales Charge.” Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - Summit Global Investments - SGI U.S. Large Cap Equity Fund	Class I Shares	Class A Shares		Class C Shares
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	none	5.25%		none
Maximum Deferred Sales Charge (Load)	none	none	[1]	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends	none	none		none
Redemption Fee (as a percentage of amount redeemed, if applicable)	none	none		none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Summit Global Investments - SGI U.S. Large Cap Equity Fund		Class I Shares	Class A Shares	Class C Shares
Management Fees		0.70%	0.70%	0.70%
Distribution and/or Service (12b-1) Fees		none	0.25%	1.00%
Other Expenses	[1]	0.23%	0.23%	0.23%
Total Annual Fund Operating Expenses		0.93%	1.18%	1.93%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Class A Shares or Class C Shares or $1,000,000 in the Class I Shares of the Fund and for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - Summit Global Investments - SGI U.S. Large Cap Equity Fund - USD ($)	One Year	Three Years	Five Years	Ten Years
Class I Shares	9,489	28,138	48,363	106,722
Class A Shares	639	866	1,111	1,812
Class C Shares	196	592	1,012	2,185

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. For the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 104% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund will invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities, primarily common stocks, of companies within the Russell 1000^® Index and S&P 500^® Index. The Fund’s investments will generally consist of securities, which may include common stocks, preferred stocks, warrants to acquire common stock, and securities convertible into common stock. The Fund purchases equity securities traded in the U.S. on registered exchanges or the over-the-counter market. The Fund may also invest in other registered investment companies, including exchange-traded funds (“ETFs”).

Summit Global Investments, LLC (the “Adviser”) attempts to lower the Fund’s market risk by investing in U.S. equity securities that lower the overall volatility of the Fund’s portfolio as compared to the S&P 500^® Index. Volatility is a statistical measurement of the magnitude of up and down fluctuations in the value of a financial instrument or index. The Fund invests in stocks that often exhibit less volatile stock price patterns, strengthening business metrics (i.e., earnings, debt, return on assets, competition, customers, industry, etc.) and quantitative factors such as earnings variability, leverage, volatility, price/book, price/cash flow, etc. In addition, the Adviser reviews the idiosyncratic risks associated with each stock if these risks are deemed elevated with increased downside risks, due to environmental, social and/or governance (“ESG”) issues. The Adviser selects securities for the Fund that it anticipates will produce a portfolio with less volatility with more capital protection and consistent returns. While the Adviser attempts to manage the Fund’s volatility, there is no guarantee that the strategy will be successful or that the Fund’s portfolio will not experience periods of volatility.

The Fund may sell a stock if the Adviser identifies fundamental, ESG, or legal risks and/or if the risk/return ranking declines due to increasing risk and/or decreasing return potential. The Fund may also decrease weight in an investment for risk control purposes.

Principal Risks

Loss of money is a risk of investing in the Fund. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

■ Common Stock Risk. Investments in common stocks are subject to market, economic and business risks that will cause their price to fluctuate over time. Therefore, an investment in the Fund may be more suitable for long-term investors who can bear the risk of these fluctuations. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of bonds and preferred stock take precedence over the claims of those who own common stock.

■ Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

■ Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

■ Environmental, Social and Governance Investing Risk. ESG investing risk is the risk stemming from the environmental, social and governance factors that the Fund applies in selecting securities. The Fund intends to invest in companies with measurable high ESG ratings relative to their sector peers, and screen out particular companies that do not meet its ESG criteria. This may affect the Fund’s exposure to certain companies or industries and cause the Fund to forego certain investment opportunities. The Fund’s results may be lower than other funds that do not seek to invest in companies based on ESG ratings and/or screen out certain companies or industries. The Fund seeks to identify companies that it believes may have a societal impact outcome, but investors may differ in their views of what constitutes positive or negative societal impact outcomes. As a result, the Fund may invest in companies that do not reflect the beliefs and values of any particular investor.

■ High Portfolio Turnover Risk. The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions and cause higher levels of current tax liability to shareholders of the Fund. A portfolio turnover rate of 100% is considered to be high. For the last fiscal year, the annual portfolio turnover rate of the Fund was lower than 100%, but the Fund’s portfolio turnover rate is expected to vary from year to year. The Adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

■ Investment Companies and ETFs Risk. Investing in other investment companies, including ETFs, may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. The risk of owning an investment company or ETF generally reflects the risks of owning the underlying investments the investment company or ETF holds. The Fund may incur brokerage fees in connection with its purchase of ETF shares. Certain ETFs maybe thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

■ Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium- capitalization stocks.

■ Low Volatility Risk. Although subject to the risks of common stocks, low volatility stocks are seen as having a lower risk profile than the overall markets. However, a portfolio comprised of low volatility stocks may not produce investment exposure that has lower variability to changes in such stocks’ price levels. Investing in low volatility stocks may limit the Fund’s gains in rising markets.

■ Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

■ Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes will produce less volatility, there is no guarantee that the stocks will perform as expected.

■ Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

■ Opportunity Risk. As with all mutual funds, the Fund is subject to the risk of missing out on an opportunity because the assets necessary to take advantage of it are tied up in less advantageous investments.

■ Warrants Risk. The purchase of warrants involves the risk that the Fund could lose the purchase value of a warrant if the right to subscribe to additional shares is not executed prior to the warrant’s expiration. Also, the purchase of warrants involves the risk that the effective price paid for the warrant added to the subscription price of the related security may exceed the value of the subscribed security’s market price such as when there is no movement in the level of the underlying security.

Performance Information

The chart below illustrates the performance of the Fund’s Class I Shares (the Class with the longest performance). The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information may be obtained at www.sgiam.com or by calling 1-855-744-8500.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31 *

^* The returns in the bar chart are for Class I Shares. Class A Shares and Class C Shares would have substantially similar annual returns because each class of shares would have invested in the same portfolio of securities, and the annual returns would differ only to the extent that the classes have different expenses. The Fund’s Class A Shares are subject to a sales charge (load). Sales charges (loads) or account fees are not reflected in the bar chart and if these amounts were reflected, returns would be less than those shown.

Best and Worst Quarterly Performance (for the period reflected in the chart above):

Best Quarter: 13.53% (quarter ended March 31, 2013)
Worst Quarter: -13.11% (quarter ended December 31, 2018)

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

The following table, which includes all applicable sales charges (loads) and account fees, compares the Fund’s Class I, Class A and Class C Shares average annual total returns for the periods indicated to the average annual total returns of a broad-based securities market index for the same periods. Past performance (before and after taxes) is not necessarily an indicator of how the Fund will perform in the future.

Average Annual Total Returns - Summit Global Investments - SGI U.S. Large Cap Equity Fund		1 Year	5 Years	Since Inception	Inception Date
Class I Shares	[1]	27.01%	10.80%	12.57%	Feb. 29, 2012
Class I Shares | After Taxes on Distributions	[1],[2]	26.18%	9.50%	11.40%	Feb. 29, 2012
Class I Shares | After Taxes on Distributions and Sales	[1],[2]	16.52%	8.25%	9.95%	Feb. 29, 2012
Class A Shares	[3]	20.02%		10.11%	Oct. 29, 2015
Class C Shares	[4]	25.70%		11.43%	Dec. 31, 2015
S&P 500® Index  (reflects reinvestment of dividends and no deductions for fees, expenses or taxes)		31.49%	11.70%	13.96%	Feb. 29, 2012

[1] A contingent deferred sales charge of 1.00% is assessed on certain redemptions of Class A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[1] "Other Expenses" includes fees and expenses reimbursed by the Fund during the most recent fiscal year.

[1] Class I Shares of the Fund commenced operations on February 29, 2012.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").

[3] Class A Shares of the Fund commenced operations on October 29, 2015.

[4] Class C Shares of the Fund commenced operations on December 31, 2015.

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Summit Global Investments | SGI Global Equity Fund

SUMMARY SECTION     Global Equity Fund

Investment Objective

The investment objective of the SGI Global Equity Fund (for this section only, the “Fund”) is to seek long-term capital appreciation. There can be no guarantee that the Fund will achieve its investment objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information — Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information — Reducing or Eliminating the Front-End Sales Charge.” Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - Summit Global Investments - SGI Global Equity Fund	Class I Shares	Class A Shares		Class C Shares
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	none	5.25%		none
Maximum Deferred Sales Charge (Load)	none	none	[1]	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends	none	none		none
Redemption Fee (as a percentage of amount redeemed, if applicable)	none	none		none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Summit Global Investments - SGI Global Equity Fund		Class I Shares	Class A Shares	Class C Shares
Management Fees		0.70%	0.70%	0.70%
Distribution and/or Service (12b-1) Fees		none	0.25%	1.00%
Other Expenses	[1]	0.41%	0.41%	0.41%
Total Annual Fund Operating Expenses		1.11%	1.36%	2.11%
Fee Waivers and/or Expense Reimbursements	[2]	(0.27%)	(0.27%)	(0.27%)
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements		0.84%	1.09%	1.84%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $1,000,000 in Class I Shares or $10,000 in Class A Shares or Class C Shares of the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that each year your investment has a 5% return and Fund operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - Summit Global Investments - SGI Global Equity Fund - USD ($)	One Year	Three Years	Five Years	Ten Years
Class I Shares	8,575	32,606	58,544	132,750
Class A Shares	630	908	1,206	2,052
Class C Shares	187	635	1,109	2,420

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year. For the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 74% of the average value of its portfolio.

Principal Investment Strategies

Under normal market conditions, the Fund invests at least 80% of the value of its net assets, plus any borrowings for investment purposes, in equity securities. The Fund invests, under normal market conditions, significantly (ordinarily at least 40% - unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund defines non-U.S. companies as companies that (i) are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets or derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States.

The Fund’s investments in equity securities include, without limitation, common stocks, preferred stocks, warrants to acquire common stock, and securities convertible into common stock.The Fund’s investments will generally consist of securities, which may include common stocks, preferred stocks, warrants to acquire common stock, and securities convertible into common stock. The Fund purchases equity securities traded on registered exchanges or the over-the-counter market. The Fund may invest in securities of foreign issuers either directly or through depository receipts, including American Depository Receipts (“ADRs”). The Fund may also invest in other registered investment companies, including exchange-traded funds (“ETFs”). The Fund may invest in or have exposure to companies of any size, but primarily invests in large- and mid- capitalization companies.

The Adviser attempts to lower the Fund’s market risk by investing in equity securities that lower the overall volatility of the Fund’s portfolio as compared to global equity benchmarks. Volatility is a statistical measurement of the magnitude of up and down fluctuations in the value of a financial instrument or index. The Fund invests in stocks that exhibit less volatile stock price patterns, strengthening business metrics (i.e., earnings, debt, return on assets, competition, customers, industry, etc.) and quantitative factors such as earnings variability, leverage, volatility, price/book, price/cash flow, etc. In addition, the Adviser reviews the idiosyncratic risks associated with each stock if these risks are deemed elevated with increased downside risks, due to environmental, social and/or governance (“ESG”) issues. The Adviser selects securities for the Fund that it anticipates will produce a portfolio with less volatility with more capital protection and consistent returns. While the Adviser attempts to manage the Fund’s volatility, there is no guarantee that the strategy will be successful or that the Fund’s portfolio will not experience periods of volatility.

The Fund may sell a stock if the Adviser identifies fundamental, ESG, or legal risks and/or if the risk/return ranking declines due to increasing risk and/or decreasing return potential. The Fund may also decrease weight in an investment for risk control purposes.

Principal Risks

Loss of money is a risk of investing in the Fund. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

■ Common Stock Risk. Investments in common stocks are subject to market, economic and business risks that will cause their price to fluctuate over time. Therefore, an investment in the Fund may be more suitable for long-term investors who can bear the risk of these fluctuations.

■ Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

■ Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

■ Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

■ Environmental, Social and Governance Investing Risk. ESG investing risk is the risk stemming from the environmental, social and governance factors that the Fund applies in selecting securities. The Fund intends to invest in companies with measurable high ESG ratings relative to their sector peers, and screen out particular companies that do not meet its ESG criteria. This may affect the Fund’s exposure to certain companies or industries and cause the Fund to forego certain investment opportunities. The Fund’s results may be lower than other funds that do not seek to invest in companies based on ESG ratings and/or screen out certain companies or industries. The Fund seeks to identify companies that it believes may have a societal impact outcome, but investors may differ in their views of what constitutes positive or negative societal impact outcomes. As a result, the Fund may invest in companies that do not reflect the beliefs and values of any particular investor.

■ Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

■ Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

■ High Portfolio Turnover Risk. The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions and cause higher levels of current tax liability to shareholders of the Fund. A portfolio turnover rate of 100% is considered to be high. For the last fiscal year, the annual portfolio turnover rate of the Fund was lower than 100%, but the Fund’s portfolio turnover rate is expected to vary from year to year. The Adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

■ Investment Companies and ETFs Risk. Investing in other investment companies, including ETFs, may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. The risk of owning an investment company or ETF generally reflects the risks of owning the underlying investments the investment company or ETF holds. The Fund may incur brokerage fees in connection with its purchase of ETF shares. Certain ETFs maybe thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

■ Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium- capitalization stocks.

■ Low Volatility Risk. Although subject to the risks of common stocks, low volatility stocks are seen as having a lower risk profile than the overall markets. However, a portfolio comprised of low volatility stocks may not produce investment exposure that has lower variability to changes in such stocks’ price levels. Investing in low volatility stocks may limit the Fund’s gains in rising markets.

■ Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

■ Market Risk. The NAV of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes will produce less volatility, there is no guarantee that the stocks will perform as expected.

■ Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

■ Opportunity Risk. As with all mutual funds, the Fund is subject to the risk of missing out on an opportunity because the assets necessary to take advantage of it are tied up in less advantageous investments.

■ Warrants Risk. The purchase of warrants involves the risk that the Fund could lose the purchase value of a warrant if the right to subscribe to additional shares is not executed prior to the warrant’s expiration. Also, the purchase of warrants involves the risk that the effective price paid for the warrant added to the subscription price of the related security may exceed the value of the subscribed security’s market price such as when there is no movement in the level of the underlying security.

Performance Information

Returns shown were generated under the management of the Fund’s former investment adviser and reflect a previous investment strategy. The Fund operated as a series of Scotia Institutional Funds prior to the close of business on March 21, 2014 (the “Predecessor Fund”). Before the Fund commenced operations, all of the assets and liabilities of the Predecessor Fund were transferred to the Fund in a tax-free reorganization (the “Reorganization”). The Reorganization occurred on March 21, 2014. As a result of the Reorganization, the Fund assumed the performance and accounting history of the Predecessor Fund prior to the date of the Reorganization. The performance shown for periods prior to March 21, 2014 is that of the Predecessor Fund.

The Board approved the Adviser to serve as the Global Equity Fund’s investment adviser effective January 1, 2017. Returns shown for periods prior to January 1, 2017 were generated under the management of the Global Equity Fund’s former investment adviser.

The chart below illustrates the performance of the Fund’s Class I Shares. Performance for Class A Shares and Class C Shares is not shown because Class A Shares and Class C Shares had not commenced operations prior to the date of this Prospectus. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information may be obtained at www.sgiam.com or by calling 855-744-8500.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Best and Worst Quarterly Performance (for the period reflected in the chart above):

Best Quarter: 23.87% (quarter ended September 30, 2013)
Worst Quarter: -16.50% (quarter ended September 30, 2011)

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

The table below compares the Fund’s Class I Shares average annual total returns for the periods indicated to the average annual total returns of a broad-based securities market index for the same periods. Past performance (before and after taxes) is not necessarily an indicator of how the Fund will perform in the future.

Average Annual Total Returns - Summit Global Investments - SGI Global Equity Fund		1 Year	5 Years	10 Years	Since Inception	[1]	Inception Date
Class I Shares		24.02%	7.99%	13.92%	16.62%		Apr. 01, 2009
Class I Shares | After Taxes on Distributions	[2]	23.17%	7.34%	12.75%	15.07%		Apr. 01, 2009
Class I Shares | After Taxes on Distributions and Sales		15.09%	6.17%	11.22%	13.46%		Apr. 01, 2009
MSCI ACWI Index (reflects no deductions for fees, expenses or taxes)		26.60%	8.41%	8.79%	12.36%		Apr. 01, 2009

[1] A contingent deferred sales charge of 1.00% is assessed on certain redemptions of Class A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[1] "Other Expenses" for Class A Shares and Class C Shares, which had not commenced operations as of the date of this prospectus, are estimated based on Class I Shares for the current fiscal year.

[2] Summit Global Investments, LLC (the "Adviser"), the Fund's investment adviser, has contractually agreed to waive management fees and reimburse expenses through February 28, 2021 to the extent that Total Annual Fund Operating Expenses (excluding certain items discussed below) exceed 0.84%, 1.09%, and 1.84% of the Fund's average daily net assets attributable to Class I Shares, Class A and Class C Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and are expected to cause net Total Annual Fund Operating Expenses to exceed 0.84%,1.09% or 1.84%, as applicable: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation may not be terminated before February 28, 2021 without the approval of the Board of Directors of The RBB Fund, Inc. (the "Company"). If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 0.84%, 1.09% and 1.84%, of the Fund's average daily net assets attributable to Class I Shares, Class A Shares and Class C Shares, respectively, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] While the Predecessor Fund commenced operations on March 31, 2009, the Predecessor Fund began investing consistent with its investment objective on April 1, 2009.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").

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Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND

SUMMARY SECTION

Investment Objective

The investment objective of the Abbey Capital Multi Asset Fund (the “Fund”) is to seek long-term capital appreciation.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund (the “Shares”). You may qualify for sales charge discounts if you invest, or agree to invest in the future, at least $25,000 in Class A Shares of the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information – Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information – Reducing or Eliminating the Front-End Sales Charge.” Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - Abbey Capital - ABBEY CAPITAL MULTI ASSET FUND	CLASS I SHARES	CLASS A SHARES		CLASS C SHARES
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	none	5.75%		none
Maximum Deferred Sales Charge (Load)	none	none	[1]	1.00%	[2]
Maximum Sales Charge (Load) Imposed on Reinvested Dividends	none	none		none
Redemption Fee (as a percentage of amount redeemed, if applicable)	none	none		none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Abbey Capital - ABBEY CAPITAL MULTI ASSET FUND		CLASS I SHARES	CLASS A SHARES		CLASS C SHARES
Management Fees	[1]	1.77%	1.77%		1.77%
Distribution and/or Service (12b-1) Fees		none	0.25%		1.00%
Other Expenses		0.50%	0.50%	[2]	0.50%	[2]
Total Annual Fund Operating Expenses		2.27%	2.52%		3.27%
Fee Waivers and/or Expense Reimbursements	[3]	(0.48%)	(0.48%)		(0.48%)
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements		1.79%	2.04%		2.79%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in Class A and Class C Shares, and $1,000,000 in Class I Shares, of the Fund for the time periods indicated and then redeem all of your Shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same (taking into account the contractual expense limitation until its expiration). Although your actual costs may be higher or lower, based on these assumptions your costs of investing in the Fund would be:

Expense Example - Abbey Capital - ABBEY CAPITAL MULTI ASSET FUND - USD ($)	One Year	Three Years	Five Years	Ten Years
CLASS I SHARES	18,187	66,333	117,142	256,813
CLASS A SHARES	770	1,271	1,798	3,233
CLASS C SHARES	382	962	1,666	3,535

You would pay the following expenses on Class C Shares if you did not redeem your shares at the end of the period:

Expense Example, No Redemption	One Year	Three Years	Five Years	Ten Years
Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND | CLASS C SHARES | USD ($)	282	962	1,666	3,535

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 0% of the average value of its portfolio. In accordance with industry practice, derivative instruments and instruments with a maturity of one year or less at the time of acquisition are excluded from the calculation of the portfolio turnover rate, which leads to the 0% portfolio turnover rate reported above. If those instruments were included in the calculation, the Fund would have a higher portfolio turnover rate.

Principal Investment Strategies

The Fund seeks to achieve its investment objective by allocating its assets among a “Managed Futures” strategy, a “Long U.S. Equity” strategy and a “Fixed Income” strategy.

The Managed Futures strategy will be achieved by the Fund investing in managed futures investments, including (i) options, (ii) futures, (iii) forwards, (iv) spot contracts, or (v) swaps, including total return swaps, each of which may be tied to (i) commodities, (ii) financial indices and instruments, (iii) foreign currencies, or (iv) equity indices (the “Futures Portfolio”). The Fund may make some or all of its investments in the Futures Portfolio through Abbey Capital Multi Asset Offshore Fund Limited, a wholly-owned and controlled subsidiary of the Fund organized under the laws of the Cayman Islands (the “Subsidiary”), and may invest up to 25% of its total assets in the Subsidiary. The Adviser may allocate assets of the Subsidiary to a single Managed Futures portfolio or multiple Managed Futures portfolios that include investment styles or sub-strategies such as (i) trend following, (ii) discretionary, fundamentals-based investing with a focus on macroeconomic analysis, (iii) strategies that pursue both fundamental and technical trading approaches, (iv) other specialized approaches to specific or individual market sectors such as equities, interest rates, metals, agricultural and soft commodities, and (v) systematic trading strategies which incorporate technical and fundamental variables.

The Managed Futures strategy investments are designed to achieve capital appreciation in the financial and commodities futures markets. The Adviser intends to allocate a portion of the assets of the Fund and the Subsidiary to one or more Trading Advisers to manage in percentages determined at the discretion of the Adviser. Each current Trading Adviser is registered with the U.S. Commodity Futures Trading Commission (the “CFTC”) as a Commodity Trading Advisor (“CTA”). Trading Advisers that are not registered with the SEC as investment advisers provide advice only regarding matters that do not involve securities. The trading strategies employ several different trading styles using different research and trading methodologies, in a wide range of global financial and commodity markets operating over multiple time frames. Trading Advisers may use discretionary approaches aimed at identifying value investments and turning points in trends. The Fund invests in U.S. and non-U.S. markets and in developed and emerging markets.

The Long U.S. Equity strategy will be achieved by the Adviser targeting an allocation of approximately 50% of the Fund’s total assets in a portfolio of one or more U.S. equity index futures (the “Equity Portfolio”). The Adviser will monitor the percentage of the Fund’s total assets that form the Equity Portfolio on a daily basis. The Adviser will establish ‘rebalancing thresholds’ so that if at any time the percentage of the Fund’s total assets invested in the Equity Portfolio is above or below the target allocation of approximately 50% by a specific amount, then the Adviser will seek to rebalance the Equity Portfolio back towards its target allocation of approximately 50%. Such rebalancing thresholds will be determined by the Adviser and may be subject to change from time to time.

As part of the Long U.S. Equity strategy, the Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, futures, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, and shares of other investment companies (including exchanged-traded funds (“ETFs”)) and real estate investment trusts (“REITs”). The Fund may also participate as a purchaser in initial public offerings of securities (“IPO”), a company’s first offering of stock to the public. The Fund defines United States companies as companies (i) that are organized under the laws of the United States; (ii) whose principal trading market is in a the United States; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, within the United States.

The Fixed Income strategy invests the Fund’s assets primarily in investment grade fixed income securities (of all durations and maturities) in order to generate interest income and capital appreciation, which may add diversification to the returns generated by the Fund’s Managed Futures and Long U.S. Equity strategies. The level of the Fund’s assets invested in the Fixed Income Strategy will be managed and rebalanced pursuant to thresholds determined by the Adviser, which may be subject to change from time to time. In line with these thresholds, any proceeds of maturing fixed income securities will be substantially reinvested into additional fixed income securities. The Fund must set aside liquid assets to “cover” open positions with respect to its managed futures investments. The Fixed Income strategy investments may be used to help cover the Fund’s derivative positions. The Subsidiary may also cover written options with offsetting purchased options in the same commodity and maturity, or by the purchase or sale of the underlying commodity future, in an amount great than or equal to that required by an exercised option.

To achieve its investment objective, the Fund’s Adviser will target approximately 100% exposure of the Fund’s net assets to Managed Futures strategy investments and approximately 50% exposure of the Fund’s net assets to Long U.S. Equity strategy investments. The Fund’s remaining net assets will be allocated to the Fixed Income strategy investments.

As much of the trading within the Fund is in futures markets, the Fund is likely to have cash balances surplus to margin requirements. The cash portfolio will be invested on a short-term, highly liquid, basis, to meet margin calls on the futures positions.

The Fund is “non-diversified” for purposes of the Investment Company Act of 1940, as amended, (the “1940 Act”), which means that the Fund may invest in fewer securities at any one time than a diversified fund. The Fund may not invest more than 15% of its net assets in illiquid securities. The Fund’s investments in certain derivative instruments and its short selling activities involve the use of leverage.

Generally, the Subsidiary will invest primarily in commodity futures, but it may also invest in financial futures, option and swap contracts, fixed income securities, pooled investment vehicles, including those that are not registered pursuant to the 1940 Act and other investments intended to serve as margin or collateral for the Subsidiary’s derivative positions. The Fund invests in the Subsidiary in order to gain exposure to the commodities markets within the limitations of the federal tax laws, rules and regulations that apply to regulated investment companies. Unlike the Fund, the Subsidiary may invest without limitation in commodity-linked derivatives, however, the Subsidiary will comply with the same 1940 Act asset coverage requirements with respect to its investments in commodity-linked derivatives that are applicable to the Fund’s transactions in derivatives. In addition, to the extent applicable to the investment activities of the Subsidiary, the Subsidiary will be subject to the same fundamental investment restrictions and will follow the same compliance policies and procedures as the Fund. Unlike the Fund, the Subsidiary will not seek to qualify as a regulated investment company (“RIC”) under Subchapter M of Subtitle A, Chapter 1, of the Internal Revenue Code of 1986, as amended (the “Code”). The Fund is the sole shareholder of the Subsidiary and does not expect shares of the Subsidiary to be offered or sold to other investors.

Principal Investment Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

The principal risk factors affecting shareholders’ investments in the Fund (and, indirectly, in the Subsidiary) are set forth below.

● Commodity Sector Risk: Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative instruments may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments. The prices of energy, industrial metals, precious metals, agriculture and livestock sector commodities may fluctuate widely due to factors such as changes in value, supply and demand and governmental regulatory policies. The commodity-linked securities in which the Fund invests may be issued by companies in the financial services sector, and events affecting the financial services sector may cause the Fund’s Share value to fluctuate.

● Counterparty Risk: Counterparty risk is the risk that the other party(s) to an agreement or a participant to a transaction, such as a broker or the futures commission merchant, might default on a contract or fail to perform by failing to pay amounts due or failing to fulfill the obligations of the contract or transaction.

● Credit Risk: Credit risk refers to the possibility that the issuer of the security will not be able to make principal and interest payments when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. Securities rated in the four highest categories by the rating agencies are considered investment grade but they may also have some speculative characteristics. Investment grade ratings do not guarantee that bonds will not lose value.

● Currency Risk: Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls. Forward foreign currency exchange contracts may limit potential gains from a favorable change in value between the U.S. dollar and foreign currencies. Unanticipated changes in currency pricing may result in poorer overall performance for the Fund than if it had not engaged in these contracts.

● Cyber Security Risk: Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk: The Fund’s investments in derivative instruments including options, forward currency exchange contracts, swaps and futures, which may be leveraged, may result in losses. Investments in derivative instruments may result in losses exceeding the amounts invested.

● Emerging Markets Risk: Investment in emerging market securities involves greater risk than that associated with investment in foreign securities of developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Equity and Equity-Related Securities Risk: Investments in equity securities and equity derivatives in general are subject to market risks that may cause their prices to fluctuate over time. The value of a convertible security may not increase or decrease as rapidly as the underlying common stock. Common stocks may decline over short or even extended periods of time. The purchase of rights or warrants involves the risk that the Fund could lose the purchase value of a right or warrant if the right to subscribe to additional shares is not executed prior to the right’s or warrant’s expiration. The value of securities convertible into equity securities, such as warrants or convertible debt, is also affected by prevailing interest rates, the credit quality of the issuer and any call provision.

● Fixed Income Securities Risk: Fixed income securities in which the Fund may invest are subject to certain risks, including: interest rate risk, prepayment risk and credit/default risk. Interest rate risk involves the risk that prices of fixed income securities will rise and fall in response to interest rate changes. Prepayment risk involves the risk that in declining interest rate environments prepayments of principal could increase and require the Fund to reinvest proceeds of the prepayments at lower interest rates. Credit risk involves the risk that the credit rating of a security may be lowered.

● Foreign Investments Risk: International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through “sponsored” or “unsponsored” facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders.

● Forward and Futures Risk: The successful use of forward and futures contracts draws upon the Adviser’s and Trading Advisers’ skill and experience with respect to such instruments and are subject to special risk considerations. The primary risks associated with the use of futures contracts are (a) the imperfect correlation between the change in market value of instruments held by the Fund and the price of the forward or futures contract; (b) possible lack of a liquid secondary market, and possible regulatory position limits and restrictions, for a forward or futures contract and the resulting inability to close a forward or futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s and Trading Advisers’ inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; (e) the possibility that the counterparty will default in the performance of its obligations; and (f) if the Fund has insufficient cash, it may have to sell securities from its portfolio to meet daily variation margin requirements, and the Fund may have to sell securities at a time when it may be disadvantageous to do so.

● Hedging Transactions Risk: The Adviser and Trading Advisers from time to time employ various hedging techniques. The success of the Fund’s hedging strategy will be subject to the Adviser’s and Trading Advisers’ ability to correctly assess the degree of correlation between the performance of the instruments used in the hedging strategy and the performance of the investments in the portfolio being hedged. Since the characteristics of many securities change as markets change or time passes, the success of the Fund’s hedging strategy will also be subject to the Adviser’s and Trading Advisers’ ability to continually recalculate, readjust, and execute hedges in an efficient and timely manner. For a variety of reasons, the Adviser and Trading Advisers may not seek to establish a perfect correlation between such hedging instruments and the portfolio holdings being hedged. Such imperfect correlation may prevent the Fund from achieving the intended hedge or expose the Fund to risk of loss. In addition, it is not possible to hedge fully or perfectly against any risk, and hedging entails its own cost.

● High Portfolio Turnover Risk: The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions, and cause higher levels of current tax liability to shareholders in the Fund.

● Interest Rate Risk: Interest rate risk is the risk that prices of fixed income securities generally increase when interest rates decline and decrease when interest rates increase. The Fund may lose money if short term or long term interest rates rise sharply or otherwise change in a manner not anticipated by the Adviser and Trading Advisers. It is likely there will be less governmental action in the near future to maintain low interest rates. The negative impact on fixed income securities from the resulting rate increases for that and other reasons could be swift and significant.

● Leveraging Risk: Investments in derivative instruments may give rise to a form of leverage. Trading Advisers may engage in speculative transactions which involve substantial risk and leverage, such as making short sales. The use of leverage by the Adviser and Trading Advisers may increase the volatility of the Fund. These leveraged instruments may result in losses to the Fund or may adversely affect the Fund’s net asset value (“NAV”) or total return, because instruments that contain leverage are more sensitive to changes in interest rates. The Fund may also have to sell assets at inopportune times to satisfy its obligations in connection with such transactions.

● Limiting Operating History Risk: The Fund has a limited operating history. There is a risk that the Fund will not grow or maintain an economically viable size, in which case the Board may determine to liquidate the Fund.

● Management Risk: The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Manager Risk: If the Adviser and Trading Advisers make poor investment decisions, it will negatively affect the Fund’s investment performance.

● Market Risk: The NAV of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money.

● Multi-Manager Dependence Risk: The success of the Fund’s investment strategy depends both on the Adviser’s ability to select Trading Advisers and to allocate assets to those Trading Advisers and on each Trading Adviser’s ability to execute the relevant strategy and select investments for the Fund and the Subsidiary. The Trading Advisers’ investment styles may not always be complementary, which could adversely affect the performance of the Fund.

● New Adviser Risk: The Trading Advisers may be newly registered or not registered with the SEC and/or have not previously managed a mutual fund. Accordingly, investors in the Fund bear the risk that a Trading Adviser’s inexperience may limit its effectiveness.

● Non-Diversification Risk: The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk: Purchasing and writing put and call options are highly specialized activities and entail greater than ordinary investment risks. The Fund may not fully benefit from or may lose money on an option if changes in its value do not correspond as anticipated to changes in the value of the underlying securities.

● Quantitative Trading Strategies Risk: The Adviser and Trading Advisers may use quantitative methods to select investments. Securities or other investments selected using quantitative methods may perform differently from the market as a whole or from their expected performance for many reasons, including factors used in building the quantitative analytical framework, the weights placed on each factor, and changing sources of market returns, among others. Any errors or imperfections in quantitative analyses or models, or in the data on which they are based, could adversely affect the ability of the Adviser or a Trading Adviser to use such analyses or models effectively, which in turn could adversely affect the Fund’s performance. There can be no assurance that these methodologies will help the Fund to achieve its investment objective.

● Subsidiary Risk: By investing in the Subsidiary, the Fund is indirectly exposed to the risks associated with the Subsidiary’s investments. The derivatives and other investments held by the Subsidiary are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the fund. The Subsidiary is not registered under the 1940 Act, and, unless otherwise noted in this Prospectus, is not subject to all the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to continue to operate as it does currently and could adversely affect the Fund.

● Tax Risk: In order to qualify as a RIC, the Fund must meet certain requirements regarding the source of its income, the diversification of its assets and the distribution of its income. Under the test regarding the source of a RIC’s income, at least 90% of the gross income of the RIC each year must be qualifying income, which consists of dividends, interest, gains on investment assets and other categories of investment income. In 2006, the Internal Revenue Service (“IRS”) published a ruling that income realized from swaps with respect to a commodities index would not be qualifying income. The Fund’s investment in the Subsidiary is expected to provide the Fund with exposure to the commodities markets within the limitations of the Code for qualification as a RIC, but there is a risk that the IRS could assert that the income derived from the Fund’s investment in the Subsidiary and certain commodity-linked structured notes will not be considered qualifying income for purposes of the Fund remaining qualified as a RIC for U.S. federal income tax purposes. If the Fund were to fail to qualify as a RIC and became subject to federal income tax, shareholders of the Fund would be subject to diminished returns. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or its Subsidiary to operate as described in this Prospectus and the SAI and could adversely affect the Fund. For example, the Cayman Islands does not currently impose any income, corporate or capital gains tax or withholding tax on the Subsidiary. If Cayman Islands law changes such that the Subsidiary must pay Cayman Islands taxes, Fund shareholders would likely suffer decreased investment returns.

Performance Information

The bar chart and table below illustrate the long-term performance of the Fund. The bar chart below shows how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of all dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Updated performance information is available online at www.abbeycapital.com or by calling 1-844-261-6484 (toll free).

The Fund commenced operations as a series of the Company on April 11, 2018, when all of the assets of Abbey Global LP (the “Predecessor Fund”) transferred to Class I Shares of the Fund. The Fund’s objectives, policies, guidelines and restrictions are in all material respects equivalent to the Predecessor Fund. Accordingly, the performance information shown below for periods prior to April 11, 2018 is that of the Predecessor Fund. The Predecessor Fund was not registered under the 1940 Act, and thus was not subject to certain investment and operational restrictions that are imposed by the 1940 Act. If the Predecessor Fund had been registered under the 1940 Act, its performance may have been adversely affected. Accordingly, future Fund performance may be different than the Predecessor Fund’s restated past performance. The Predecessor Fund was not a regulated investment company under Subchapter M of the Internal Revenue Code and therefore did not distribute current or accumulated earnings and profits and was not subject to the diversification and source of income requirements applicable to regulated investment companies. Monthly returns since the inception of the Predecessor Fund are provided in Appendix A of the Prospectus.

Total Returns for the Calendar Year s Ended December 31

During the period shown in the chart, the highest quarterly return was 17.10% (for the quarter ended September 30, 2010) and the lowest quarterly return was -15.91% (for the quarter ended September 30, 2011).

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

The following table compares the average annual total returns for the Fund’s Class I shares, including the Predecessor Fund, before and after taxes for the past calendar year, five-year, ten-year and since inception periods to the average annual total returns of a broad-based securities market index for the same periods. Average annual returns for Class A Shares and Class C Shares of the Fund are not included because they had not commenced operations prior to the date of this Prospectus.

Average Annual Total Returns - Abbey Capital - ABBEY CAPITAL MULTI ASSET FUND		1 Year	5 Years	10 Years	Since Inception	Inception Date
CLASS I SHARES		21.64%	6.04%	9.87%	10.12%	May 14, 2002
CLASS I SHARES | After Taxes on Distributions	[1]	16.33%	4.47%	9.05%	9.66%	May 14, 2002
CLASS I SHARES | After Taxes on Distributions and Sales	[1]	12.98%	4.08%	7.79%	8.56%	May 14, 2002
S&P 500® Total Return Index (reflects no deduction for fees, expenses and taxes)		31.49%	11.70%	13.56%	8.50%	May 14, 2002

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Class A Shares made within 12 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The CDSC applies to redemptions of Class C Shares made within 12 months of purchase and will be assessed on an amount equal to the lesser of the offering price at the time of purchase of the shares redeemed and the net asset value of the shares redeemed at the time of redemption.

[1] Management Fees include advisory fees paid to both Abbey Capital Limited (the "Adviser") and one or more trading advisers (the "Trading Advisers"). There are no performance fees charged by the Adviser or Trading Advisers either at the Fund or at the Fund's wholly-owned Subsidiary.

[2] "Other Expenses" for Class A Shares and Class C Shares, which had not commenced operations as of the date of this Prospectus, are based on Class I Shares for the current fiscal year.

[3] The Adviser has contractually agreed to waive its advisory fee and/or reimburse expenses in order to limit Total Annual Fund Operating Expenses (excluding certain items discussed below) to 1.79%, 2.04% and 2.79% of the Fund's average daily net assets attributable to Class I Shares, Class A Shares and Class C Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total Annual Fund Operating Expenses to exceed 1.79%, 2.04% or 2.79%, as applicable: acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 for Class I Shares, Class A Shares and Class C Shares, and may not be terminated prior to that date without the approval of the Board of Directors of The RBB Fund, Inc. (the "Company"). If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.79%, 2.04% and 2.79%, as applicable, the Adviser may recoup any waived or reimbursed amounts from the Fund within three years from the date on which such waiver or reimbursement was made by the Adviser, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

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Institutional Class Prospectus | Boston Partners All-Cap Value Fund

SUMMARY SECTION — BOSTON PARTNERS ALL-CAP VALUE FUND

Investment Objective

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners All-Cap Value Fund Institutional Class
Management Fees	0.70%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.12%
Acquired fund fees and expenses	0.01%	[1]
Total Annual Fund Operating Expenses	0.83%
Fee Waivers and/or Expense Reimbursements	(0.03%)	[2]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	0.80%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | Boston Partners All-Cap Value Fund | Institutional Class | USD ($)	817	2,619	4,575	10,226

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 33% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers across the capitalization spectrum and identified by the Adviser as having value characteristics.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals, such as return on equity and earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may also invest up to 20% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

The Fund may invest up to 10% of its net assets in securities that can be converted into common stock, such as certain debt securities and preferred stock.

The Fund may hedge overall portfolio exposure up to 40% of its net assets through the purchase and sale of index and individual put and call options.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may “cover” a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners All-Cap Value Fund’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	13.23% (quarter ended December 31, 2011)
Worst Quarter:	-17.49% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Institutional Class Prospectus - Boston Partners All-Cap Value Fund		1 Year	5 Years	10 Years
Institutional Class		27.88%	9.02%	12.03%
Institutional Class | After Taxes on Distributions	[1]	27.09%	7.82%	10.94%
Institutional Class | After Taxes on Distributions and Sales		17.05%	6.92%	9.76%
Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)		26.26%	8.20%	11.71%

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 0.80% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.80%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 0.80% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Prospectus [Line Items]

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Document Type

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485BPOS

Document Period End Date

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Aug. 31, 2019

Entity Registrant Name

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RBB FUND, INC.

Entity Central Index Key

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0000831114

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N-1A

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Feb. 28, 2020

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Feb. 28, 2020

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Feb. 28, 2020

Institutional Class Prospectus | Boston Partners Long/Short Equity Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — BOSTON PARTNERS LONG/SHORT EQUITY FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation while reducing exposure to general equity market risk. The Fund seeks a total return greater than that of the S&P 500^® Index over a full market cycle.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 64% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

64.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage. The Fund invests, both long and short, in securities principally traded in the United States markets. The Fund may invest in securities of companies operating for three years or less (“unseasoned issuers”). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the United States equity market generally. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities. Under normal circumstances, the Adviser expects that the Fund’s long positions will not exceed approximately 125% of the Fund’s net assets.

The Fund’s long and short positions may involve (without limit) equity securities of foreign issuers that are traded in the markets of the United States. The Fund may also invest up to 20% of its total assets directly in equity securities of foreign issuers.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations. High yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund’s assets could impede portfolio management or the Fund’s ability to meet redemption requests or other current obligations.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Equity Fund’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	13.47% (quarter ended December 31, 2010)
Worst Quarter:	-9.97% (quarter ended June 30, 2010)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods. Although the Fund compares its average total return to a broad-based securities market index, the Fund seeks returns that are not correlated to securities market returns. The Fund seeks to achieve a 12-15% return over a full market cycle; however, there can be no guarantee that such returns will be achieved.

Institutional Class Prospectus | Boston Partners Long/Short Equity Fund | S&P 500® Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

31.49%

5 Years

rr_AverageAnnualReturnYear05

11.70%

10 Years

rr_AverageAnnualReturnYear10

13.56%

Institutional Class Prospectus | Boston Partners Long/Short Equity Fund | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

BPLSX

Management Fees

rr_ManagementFeesOverAssets

2.25%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.21%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.68%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.50%)

^[1]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.18%

One Year

rr_ExpenseExampleYear01

$ 2,211

Three Years

rr_ExpenseExampleYear03

7,850

Five Years

rr_ExpenseExampleYear05

13,755

Ten Years

rr_ExpenseExampleYear10

$ 29,757

Annual Return 2010

rr_AnnualReturn2010

26.44%

Annual Return 2011

rr_AnnualReturn2011

5.92%

Annual Return 2012

rr_AnnualReturn2012

12.47%

Annual Return 2013

rr_AnnualReturn2013

7.90%

Annual Return 2014

rr_AnnualReturn2014

4.72%

Annual Return 2015

rr_AnnualReturn2015

(1.09%)

Annual Return 2016

rr_AnnualReturn2016

22.48%

Annual Return 2017

rr_AnnualReturn2017

2.77%

Annual Return 2018

rr_AnnualReturn2018

(15.47%)

Annual Return 2019

rr_AnnualReturn2019

9.12%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.47%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.97%)

1 Year

rr_AverageAnnualReturnYear01

9.12%

5 Years

rr_AverageAnnualReturnYear05

2.80%

10 Years

rr_AverageAnnualReturnYear10

6.93%

Institutional Class Prospectus | Boston Partners Long/Short Equity Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

6.69%

^[2]

5 Years

rr_AverageAnnualReturnYear05

1.50%

^[2]

10 Years

rr_AverageAnnualReturnYear10

5.21%

^[2]

Institutional Class Prospectus | Boston Partners Long/Short Equity Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

7.10%

5 Years

rr_AverageAnnualReturnYear05

2.10%

10 Years

rr_AverageAnnualReturnYear10

5.28%

[1] Effective February 28, 2020, the Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class exceeds 1.96% of the average daily net assets attributable to the Fund's Institutional Class shares. Because dividend expenses on short sales, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 1.96%. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.96% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement. Prior to February 28, 2020, the Fund's Institutional Class fee cap was 2.50%.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

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Entity Registrant Name

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RBB FUND, INC.

Entity Central Index Key

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Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — WPG PARTNERS SMALL/MICRO CAP VALUE FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks capital appreciation by investing primarily in common stocks, securities convertible into common stocks and in special situations.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 79% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

79.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Currently, the Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in equity securities of U.S. companies that, at the time of purchase, have a market capitalization that is within the range of the market capitalization of issuers in the Russell 2000^® Value Index. As of November 30, 2019, the median market capitalization of the companies in the Russell 2000^® Value Index is $666 million and the largest stock is $6.7 billion. The Fund may invest in depositary receipts and equity securities of foreign companies. Although the Fund invests primarily in common stocks, the Fund may invest in all types of equity and equity-related securities, including (without limitation):

● Securities convertible into common stocks.

● Shares of real estate investment trusts (“REITs”).

● Warrants and rights to purchase common stocks.

● Preferred stocks.

● Exchange-traded limited partnerships.

Special Situations: The Fund may invest in companies that may experience unusual and possibly unique developments which may create a special opportunity for significant returns. Special situations include: significant technological improvements or important discoveries; reorganizations, recapitalizations or mergers; favorable resolutions of litigation; new management or material changes in company policies; and actual or potential changes in control of a company.

Strategies: The Adviser uses a value approach to select the Fund’s investments. Using this investment style, the Adviser seeks securities selling at substantial discounts to their underlying values and then holds these securities until the market values reflect what the Adviser believes to be their intrinsic values. The Adviser employs a bottom-up strategy, focusing on undervalued industries that the Adviser believes are experiencing positive change. The Adviser then uses both qualitative and quantitative methods to assess a security’s potential value. The portfolio managers managing the Fund meet with a multitude of companies annually to identify companies with increasing returns on capital in their core businesses which are selling at attractive valuations.

Factors the Adviser looks for in selecting investments include (without limitation):

● Increasing returns on invested capital.

● Companies who have demonstrated an ability to generate high return on invested capital (ROIC).

● Companies which provide solid cash flows with appropriate capital.

● Potential catalysts such as new products, cyclical upturns and changes in management.

● Low market valuations relative to earnings forecast, book value, cash flow and sales.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Rights and Warrants Risk. The purchase of rights or warrants involves the risk that the Fund could lose the purchase value of a right or warrant if the right to subscribe to additional shares is not executed prior to the right’s or warrant’s expiration. Also, the purchase of rights and/or warrants involves the risk that the effective price paid for the right and/or warrant added to the subscription price of the related security may exceed the value of the subscribed security’s market price such as when there is no movement in the level of the underlying security.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

● Special Situations Risk. The Fund will seek to benefit from “special situations,” such as mergers, reorganizations, or other unusual events expected to affect a particular issuer. There is a risk that the “special situation” might not occur or involve longer time frames than originally expected, which could have a negative impact on the price of the issuer’s securities and fail to produce gains or produce a loss for the Fund.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the WPG Partners Small/Micro Cap Value Fund’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	15.93% (quarter ended March 31, 2012)
Worst Quarter:	-25.00% (quarter ended September 30, 2011)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

In certain cases, the figure representing "Returns After Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund | Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

22.39%

5 Years

rr_AverageAnnualReturnYear05

6.99%

10 Years

rr_AverageAnnualReturnYear10

10.56%

Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund | Institutional Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

WPGTX

Management Fees

rr_ManagementFeesOverAssets

0.80%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.43%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.23%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[1]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.10%

One Year

rr_ExpenseExampleYear01

$ 1,121

Three Years

rr_ExpenseExampleYear03

3,775

Five Years

rr_ExpenseExampleYear05

6,632

Ten Years

rr_ExpenseExampleYear10

$ 14,772

Annual Return 2010

rr_AnnualReturn2010

26.10%

Annual Return 2011

rr_AnnualReturn2011

(11.95%)

Annual Return 2012

rr_AnnualReturn2012

22.88%

Annual Return 2013

rr_AnnualReturn2013

42.08%

Annual Return 2014

rr_AnnualReturn2014

(3.62%)

Annual Return 2015

rr_AnnualReturn2015

(13.74%)

Annual Return 2016

rr_AnnualReturn2016

19.63%

Annual Return 2017

rr_AnnualReturn2017

5.68%

Annual Return 2018

rr_AnnualReturn2018

(21.77%)

Annual Return 2019

rr_AnnualReturn2019

23.35%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

15.93%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(25.00%)

1 Year

rr_AverageAnnualReturnYear01

23.35%

5 Years

rr_AverageAnnualReturnYear05

1.03%

10 Years

rr_AverageAnnualReturnYear10

6.99%

Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

23.14%

^[2]

5 Years

rr_AverageAnnualReturnYear05

(0.14%)

^[2]

10 Years

rr_AverageAnnualReturnYear10

5.69%

^[2]

Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

13.83%

5 Years

rr_AverageAnnualReturnYear05

0.42%

10 Years

rr_AverageAnnualReturnYear10

5.30%

[1] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time, the Fund's total annual fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.10% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In certain cases, the figure representing "Returns After Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Institutional Class Prospectus | Boston Partners Global Long/Short Fund

Prospectus [Line Items]

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Risk/Return [Heading]

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SUMMARY SECTION — BOSTON PARTNERS GLOBAL LONG/SHORT FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term growth of capital.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 99% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

99.00%

Expense Exchange Traded Fund Commissions [Text]

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You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and Fund operating expenses remain the same. Although your actual costs and returns might be different, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage. The Fund invests, both long and short, in securities issued by U.S. and non-U.S. companies of any capitalization size.

With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, including return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund's portfolio is rebalanced regularly. The Adviser assesses each investment's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell an investment held long or close out a short position that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

Under normal circumstances, the Adviser expects to sell securities short so that the Fund's portfolio is approximately 50% net long with an average of between 30% and 70% net long.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry. The Fund is non-diversified, and may invest in fewer securities at any one time than a diversified fund.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by U.S. and foreign corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by S&P Global, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

● Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the long-term performance of the Boston Partners Global Long/Short Fund's Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	4.10% (quarter ended June 30, 2015)
Worst Quarter:	-7.66% (quarter ended December 31, 2018)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Market Index Changed

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Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Institutional Class Prospectus | Boston Partners Global Long/Short Fund | MSCI® World Index - Net Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

27.67%

^[1]

5 Years

rr_AverageAnnualReturnYear05

8.74%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

8.10%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2013

^[1]

Institutional Class Prospectus | Boston Partners Global Long/Short Fund | MSCI® World Index - Gross Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

28.40%

^[1]

5 Years

rr_AverageAnnualReturnYear05

9.36%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

8.70%

^[1]

Inception Date

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Dec. 31, 2013

^[1]

Institutional Class Prospectus | Boston Partners Global Long/Short Fund | Institutional Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

BGLSX

Management Fees

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1.50%

Distribution and/or Service (12b-1) Fees

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none

Other Expenses

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0.14%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.48%

^[3]

One Year

rr_ExpenseExampleYear01

$ 2,511

Three Years

rr_ExpenseExampleYear03

7,725

Five Years

rr_ExpenseExampleYear05

13,205

Ten Years

rr_ExpenseExampleYear10

$ 28,160

Annual Return 2014

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1.40%

Annual Return 2015

rr_AnnualReturn2015

6.55%

Annual Return 2016

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2.36%

Annual Return 2017

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7.55%

Annual Return 2018

rr_AnnualReturn2018

(9.22%)

Annual Return 2019

rr_AnnualReturn2019

4.59%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2015

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

4.10%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(7.66%)

1 Year

rr_AverageAnnualReturnYear01

4.59%

5 Years

rr_AverageAnnualReturnYear05

2.18%

Since Inception

rr_AverageAnnualReturnSinceInception

2.05%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2013

Institutional Class Prospectus | Boston Partners Global Long/Short Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

4.27%

^[4]

5 Years

rr_AverageAnnualReturnYear05

1.99%

^[4]

Since Inception

rr_AverageAnnualReturnSinceInception

1.89%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2013

^[4]

Institutional Class Prospectus | Boston Partners Global Long/Short Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

2.95%

5 Years

rr_AverageAnnualReturnYear05

1.67%

Since Inception

rr_AverageAnnualReturnSinceInception

1.58%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2013

[1] Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 2.00% of the average daily net assets attributable to the Fund's Institutional Class shares. Because dividend expenses on short sales, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and/or expense reimbursements) are expected to exceed 2.00%. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 2.00% or the expense cap then in effect, or whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Total

Investor Class Prospectus | Boston Partners Global Long/Short Fund

SUMMARY SECTION — BOSTON PARTNERS GLOBAL LONG/SHORT FUND

Investment Objective

The Fund seeks long-term growth of capital.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Class Prospectus Boston Partners Global Long/Short Fund Investor Class
Management Fees	1.50%
Distribution and/or Service (12b-1) Fees	0.25%
Other Expenses	0.14%
Dividend expense on short sales	0.83%
Interest expense on borrowings	none
Acquired fund fees and expenses	0.01%	[1]
Total Annual Fund Operating Expenses	2.73%	[2]

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and Fund operating expenses remain the same. Although your actual costs and returns might be different, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Investor Class Prospectus | Boston Partners Global Long/Short Fund | Investor Class | USD ($)	276	798	1,346	2,841

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 99% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage The Fund invests, both long and short, in securities issued by U.S. and non-U.S. companies of any capitalization size.

With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, including return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund's portfolio is rebalanced regularly. The Adviser assesses each investment's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell an investment held long or close out a short position that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

Under normal circumstances, the Adviser expects to sell securities short so that the Fund's portfolio is approximately 50% net long with an average of between 30% and 70% net long.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry. The Fund is non-diversified and may invest in fewer securities at any one time than a diversified fund.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by U.S. and foreign corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by S&P Global, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objectives. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Global Long/Short Fund's Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year to year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	4.01% (quarter ended June 30, 2015)
Worst Quarter:	-7.65% (quarter ended December 31, 2018)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Average Annual Total Returns - Investor Class Prospectus - Boston Partners Global Long/Short Fund		1 Year	5 Years	Since Inception	Inception Date
Investor Class		4.27%	1.91%	2.15%	Apr. 11, 2014
Investor Class | After Taxes on Distributions	[1]	4.03%	1.74%	2.00%	Apr. 11, 2014
Investor Class | After Taxes on Distributions and Sales		2.69%	1.46%	1.65%	Apr. 11, 2014
MSCI World Index - Net Return (reflects no deduction for fees, expenses or taxes)	[2]	27.67%	8.74%	8.66%	Apr. 11, 2014
MSCI World Index - Gross Return (reflects no deduction for fees, expenses or taxes)	[2]	28.40%	9.36%	9.26%	Apr. 11, 2014

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Investor Class shares exceeds 2.25% of the average daily net assets attributable to the Fund's Investor Class shares. Because dividend expenses on short sales, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and/or expense reimbursements) are expected to exceed 2.25%. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 2.25% or the expense cap then in effect, or whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

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Investor Class Prospectus | Boston Partners Long/Short Research Fund

SUMMARY SECTION — BOSTON PARTNERS LONG/SHORT RESEARCH FUND

Investment Objective

The Fund seeks to provide long-term total return.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Investor Class Prospectus Boston Partners Long/Short Research Fund Investor Class
Management Fees	1.25%
Distribution and/or Service (12b-1) Fees	0.25%
Other Expenses	0.13%
Dividend expense on short sales	0.77%
Interest expense on borrowings	none
Total Annual Fund Operating Expenses	2.40%	[1]

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Investor Class Prospectus | Boston Partners Long/Short Research Fund | Investor Class | USD ($)	243	698	1,180	2,508

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 60% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund uses a hedged strategy. The Fund actively invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales (i.e. sales of securities the Fund does not own) are invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage.

The Fund invests, both long and short, in equity securities issued by large-, mid- and small (or “micro”)-cap companies, as well as other instruments that are convertible into equity securities. Equity securities in which the Fund may invest include exchange-traded and over-the-counter common and preferred stocks, warrants, rights, convertible securities, depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies and real estate investment trusts (“REITs”), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less (“unseasoned issuers”). The Fund may also invest in depository receipts and equity securities of foreign companies (denominated in either U.S. dollars or foreign currencies), put and call options, futures, indexed securities and fixed-income securities (including bonds, notes, asset-backed securities, convertible securities, Eurodollar and Yankee dollar instruments, preferred stocks and money market instruments) and high yield securities (commonly referred to as “junk bonds”). Fixed income securities in which the Fund invests include those rated between AAA and D by a nationally recognized statistical rating organization (“NRSRO”), or deemed of comparable quality by the Adviser. The Adviser may also temporarily invest uninvested cash in money market funds and similar collective investment vehicles. The Fund may also seek to increase its income by lending portfolio securities.

The Adviser determines the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the U.S. equity market by investing less than 100% of its assets in net long positions. Selection of individual securities to be held long or sold short will be based on a mix of quantitative techniques and fundamental security analysis. The Adviser selects stocks on the basis of three criteria: value, fundamental business strength and momentum. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

Although the Fund seeks to follow a hedged strategy, there can be no assurance that the Fund’s portfolio or investments will be insulated from market moves or effectively hedged against risk.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest in exchange-traded funds to the extent permitted by the Investment Company Act of 1940, as amended (“1940 Act”), and applicable SEC orders.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The principal derivative instruments in which the Fund invests are futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps. The Fund’s investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Exchange-Traded Fund Risk. Exchange-traded funds (“ETFs”) are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an Adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations (of any rating, including defaulted securities and unrated securities), including bonds and debentures, issued by corporations and business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. Less liquid securities that the fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● Indexed Securities Risk. The Fund may invest in indexed securities whose value is linked to securities indices. Most such securities have values that rise and fall according to the change in one or more specified indices and may have characteristics similar to direct investments in the underlying securities. Depending on the index, such securities may have greater volatility than the market as a whole.

● Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may be incorrect in the stocks it buys and believes to be undervalued and in stocks it sells short and believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 300%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund’s obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales “against the box” may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not “against the box” involve a form of investment leverage, and the amount of the Fund’s loss on a short sale is potentially unlimited.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Research Fund’s Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year to year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073. 

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	8.29% (quarter ended December 31, 2011)
Worst Quarter:	-9.91% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Investor Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Investor Class Prospectus - Boston Partners Long/Short Research Fund		1 Year	5 Years	Since Inception	Inception Date
Investor Class		12.28%	2.86%	6.24%	Nov. 29, 2010
Investor Class | After Taxes on Distributions	[1]	11.73%	2.32%	5.85%	Nov. 29, 2010
Investor Class | After Taxes on Distributions and Sales		7.65%	2.17%	4.98%	Nov. 29, 2010
S&P 500® Index (reflects no deduction for fees, expenses or taxes)		31.49%	11.70%	13.99%	Nov. 29, 2010

[1] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to forgo all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total Annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) exceeds 1.75% of the average daily net assets attributable to the Fund's Investor Class shares. Because short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total Annual Fund Operating Expenses (after fee waivers and expense reimbursements) are expected to exceed 1.75%.This contractual limitation is in effect until at least February 28, 2021 and may not be terminated without Board approval. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.75% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Summit Global Investments | SGI U.S. Large Cap Equity Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTIONS     U.S. Large Cap Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The SGI U.S. Large Cap Equity Fund (for this section only, the “Fund”) seeks to outperform the S&P 500^® Index over a market cycle while reducing overall volatility. There can be no guarantee that the Fund will achieve its investment objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information — Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information — Reducing or Eliminating the Front-End Sales Charge.” Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. For the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 104% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

104.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other Expenses" includes fees and expenses reimbursed by the Fund during the most recent fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example:

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Class A Shares or Class C Shares or $1,000,000 in the Class I Shares of the Fund and for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund will invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities, primarily common stocks, of companies within the Russell 1000^® Index and S&P 500^® Index. The Fund’s investments will generally consist of securities, which may include common stocks, preferred stocks, warrants to acquire common stock, and securities convertible into common stock. The Fund purchases equity securities traded in the U.S. on registered exchanges or the over-the-counter market. The Fund may also invest in other registered investment companies, including exchange-traded funds (“ETFs”).

Summit Global Investments, LLC (the “Adviser”) attempts to lower the Fund’s market risk by investing in U.S. equity securities that lower the overall volatility of the Fund’s portfolio as compared to the S&P 500^® Index. Volatility is a statistical measurement of the magnitude of up and down fluctuations in the value of a financial instrument or index. The Fund invests in stocks that often exhibit less volatile stock price patterns, strengthening business metrics (i.e., earnings, debt, return on assets, competition, customers, industry, etc.) and quantitative factors such as earnings variability, leverage, volatility, price/book, price/cash flow, etc. In addition, the Adviser reviews the idiosyncratic risks associated with each stock if these risks are deemed elevated with increased downside risks, due to environmental, social and/or governance (“ESG”) issues. The Adviser selects securities for the Fund that it anticipates will produce a portfolio with less volatility with more capital protection and consistent returns. While the Adviser attempts to manage the Fund’s volatility, there is no guarantee that the strategy will be successful or that the Fund’s portfolio will not experience periods of volatility.

The Fund may sell a stock if the Adviser identifies fundamental, ESG, or legal risks and/or if the risk/return ranking declines due to increasing risk and/or decreasing return potential. The Fund may also decrease weight in an investment for risk control purposes.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Loss of money is a risk of investing in the Fund. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

■ Common Stock Risk. Investments in common stocks are subject to market, economic and business risks that will cause their price to fluctuate over time. Therefore, an investment in the Fund may be more suitable for long-term investors who can bear the risk of these fluctuations. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of bonds and preferred stock take precedence over the claims of those who own common stock.

■ Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

■ Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

■ Environmental, Social and Governance Investing Risk. ESG investing risk is the risk stemming from the environmental, social and governance factors that the Fund applies in selecting securities. The Fund intends to invest in companies with measurable high ESG ratings relative to their sector peers, and screen out particular companies that do not meet its ESG criteria. This may affect the Fund’s exposure to certain companies or industries and cause the Fund to forego certain investment opportunities. The Fund’s results may be lower than other funds that do not seek to invest in companies based on ESG ratings and/or screen out certain companies or industries. The Fund seeks to identify companies that it believes may have a societal impact outcome, but investors may differ in their views of what constitutes positive or negative societal impact outcomes. As a result, the Fund may invest in companies that do not reflect the beliefs and values of any particular investor.

■ High Portfolio Turnover Risk. The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions and cause higher levels of current tax liability to shareholders of the Fund. A portfolio turnover rate of 100% is considered to be high. For the last fiscal year, the annual portfolio turnover rate of the Fund was lower than 100%, but the Fund’s portfolio turnover rate is expected to vary from year to year. The Adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

■ Investment Companies and ETFs Risk. Investing in other investment companies, including ETFs, may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. The risk of owning an investment company or ETF generally reflects the risks of owning the underlying investments the investment company or ETF holds. The Fund may incur brokerage fees in connection with its purchase of ETF shares. Certain ETFs maybe thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

■ Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium- capitalization stocks.

■ Low Volatility Risk. Although subject to the risks of common stocks, low volatility stocks are seen as having a lower risk profile than the overall markets. However, a portfolio comprised of low volatility stocks may not produce investment exposure that has lower variability to changes in such stocks’ price levels. Investing in low volatility stocks may limit the Fund’s gains in rising markets.

■ Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

■ Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes will produce less volatility, there is no guarantee that the stocks will perform as expected.

■ Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

■ Opportunity Risk. As with all mutual funds, the Fund is subject to the risk of missing out on an opportunity because the assets necessary to take advantage of it are tied up in less advantageous investments.

■ Warrants Risk. The purchase of warrants involves the risk that the Fund could lose the purchase value of a warrant if the right to subscribe to additional shares is not executed prior to the warrant’s expiration. Also, the purchase of warrants involves the risk that the effective price paid for the warrant added to the subscription price of the related security may exceed the value of the subscribed security’s market price such as when there is no movement in the level of the underlying security.

Risk Lose Money [Text]

rr_RiskLoseMoney

Loss of money is a risk of investing in the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The chart below illustrates the performance of the Fund’s Class I Shares (the Class with the longest performance). The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information may be obtained at www.sgiam.com or by calling 1-855-744-8500.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-855-744-8500

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.sgiam.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31 *

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

Sales charges (loads) or account fees are not reflected in the bar chart and if these amounts were reflected, returns would be less than those shown.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

^* The returns in the bar chart are for Class I Shares. Class A Shares and Class C Shares would have substantially similar annual returns because each class of shares would have invested in the same portfolio of securities, and the annual returns would differ only to the extent that the classes have different expenses. The Fund’s Class A Shares are subject to a sales charge (load). Sales charges (loads) or account fees are not reflected in the bar chart and if these amounts were reflected, returns would be less than those shown.

Best and Worst Quarterly Performance (for the period reflected in the chart above):

Best Quarter: 13.53% (quarter ended March 31, 2013)
Worst Quarter: -13.11% (quarter ended December 31, 2018)

Performance Table Heading

rr_PerformanceTableHeading

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The table below, which includes all applicable sales charges (loads) and account fees, compares the Fund's Class I, Class A and Class C Shares average annual total returns for the periods indicated to the average annual total returns of a broad-based securities market index for the same periods.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The following table, which includes all applicable sales charges (loads) and account fees, compares the Fund’s Class I, Class A and Class C Shares average annual total returns for the periods indicated to the average annual total returns of a broad-based securities market index for the same periods. Past performance (before and after taxes) is not necessarily an indicator of how the Fund will perform in the future.

Summit Global Investments | SGI U.S. Large Cap Equity Fund | S&P 500® Index  (reflects reinvestment of dividends and no deductions for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

31.49%

5 Years

rr_AverageAnnualReturnYear05

11.70%

Since Inception

rr_AverageAnnualReturnSinceInception

13.96%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 29, 2012

Summit Global Investments | SGI U.S. Large Cap Equity Fund | Class I Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

SILVX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.23%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.93%

One Year

rr_ExpenseExampleYear01

$ 9,489

Three Years

rr_ExpenseExampleYear03

28,138

Five Years

rr_ExpenseExampleYear05

48,363

Ten Years

rr_ExpenseExampleYear10

$ 106,722

Annual Return 2013

rr_AnnualReturn2013

27.71%

Annual Return 2014

rr_AnnualReturn2014

14.94%

Annual Return 2015

rr_AnnualReturn2015

3.57%

Annual Return 2016

rr_AnnualReturn2016

8.84%

Annual Return 2017

rr_AnnualReturn2017

16.41%

Annual Return 2018

rr_AnnualReturn2018

0.19%

Annual Return 2019

rr_AnnualReturn2019

27.01%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2013

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.53%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(13.11%)

1 Year

rr_AverageAnnualReturnYear01

27.01%

^[2]

5 Years

rr_AverageAnnualReturnYear05

10.80%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

12.57%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 29, 2012

^[2]

Summit Global Investments | SGI U.S. Large Cap Equity Fund | Class I Shares | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

26.18%

^[2],[3]

5 Years

rr_AverageAnnualReturnYear05

9.50%

^[2],[3]

Since Inception

rr_AverageAnnualReturnSinceInception

11.40%

^[2],[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 29, 2012

^[2],[3]

Summit Global Investments | SGI U.S. Large Cap Equity Fund | Class I Shares | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

16.52%

^[2],[3]

5 Years

rr_AverageAnnualReturnYear05

8.25%

^[2],[3]

Since Inception

rr_AverageAnnualReturnSinceInception

9.95%

^[2],[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 29, 2012

^[2],[3]

Summit Global Investments | SGI U.S. Large Cap Equity Fund | Class A Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

LVOLX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.25%

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[4]

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.23%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.18%

One Year

rr_ExpenseExampleYear01

$ 639

Three Years

rr_ExpenseExampleYear03

866

Five Years

rr_ExpenseExampleYear05

1,111

Ten Years

rr_ExpenseExampleYear10

$ 1,812

1 Year

rr_AverageAnnualReturnYear01

20.02%

^[5]

Since Inception

rr_AverageAnnualReturnSinceInception

10.11%

^[5]

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 29, 2015

^[5]

Summit Global Investments | SGI U.S. Large Cap Equity Fund | Class C Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

SGICX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses

rr_OtherExpensesOverAssets

0.23%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.93%

One Year

rr_ExpenseExampleYear01

$ 196

Three Years

rr_ExpenseExampleYear03

592

Five Years

rr_ExpenseExampleYear05

1,012

Ten Years

rr_ExpenseExampleYear10

$ 2,185

1 Year

rr_AverageAnnualReturnYear01

25.70%

^[6]

Since Inception

rr_AverageAnnualReturnSinceInception

11.43%

^[6]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2015

^[6]

[1] "Other Expenses" includes fees and expenses reimbursed by the Fund during the most recent fiscal year.

[2] Class I Shares of the Fund commenced operations on February 29, 2012.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").

[4] A contingent deferred sales charge of 1.00% is assessed on certain redemptions of Class A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[5] Class A Shares of the Fund commenced operations on October 29, 2015.

[6] Class C Shares of the Fund commenced operations on December 31, 2015.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Summit Global Investments | SGI Global Equity Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION     Global Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The investment objective of the SGI Global Equity Fund (for this section only, the “Fund”) is to seek long-term capital appreciation. There can be no guarantee that the Fund will achieve its investment objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Fund shares. You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information — Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information — Reducing or Eliminating the Front-End Sales Charge.” Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year. For the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 74% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

74.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other Expenses" for Class A Shares and Class C Shares, which had not commenced operations as of the date of this prospectus, are estimated based on Class I Shares for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $1,000,000 in Class I Shares or $10,000 in Class A Shares or Class C Shares of the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that each year your investment has a 5% return and Fund operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund invests at least 80% of the value of its net assets, plus any borrowings for investment purposes, in equity securities. The Fund invests, under normal market conditions, significantly (ordinarily at least 40% - unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund defines non-U.S. companies as companies that (i) are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets or derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States.

The Fund’s investments in equity securities include, without limitation, common stocks, preferred stocks, warrants to acquire common stock, and securities convertible into common stock.The Fund’s investments will generally consist of securities, which may include common stocks, preferred stocks, warrants to acquire common stock, and securities convertible into common stock. The Fund purchases equity securities traded on registered exchanges or the over-the-counter market. The Fund may invest in securities of foreign issuers either directly or through depository receipts, including American Depository Receipts (“ADRs”). The Fund may also invest in other registered investment companies, including exchange-traded funds (“ETFs”). The Fund may invest in or have exposure to companies of any size, but primarily invests in large- and mid- capitalization companies.

The Adviser attempts to lower the Fund’s market risk by investing in equity securities that lower the overall volatility of the Fund’s portfolio as compared to global equity benchmarks. Volatility is a statistical measurement of the magnitude of up and down fluctuations in the value of a financial instrument or index. The Fund invests in stocks that exhibit less volatile stock price patterns, strengthening business metrics (i.e., earnings, debt, return on assets, competition, customers, industry, etc.) and quantitative factors such as earnings variability, leverage, volatility, price/book, price/cash flow, etc. In addition, the Adviser reviews the idiosyncratic risks associated with each stock if these risks are deemed elevated with increased downside risks, due to environmental, social and/or governance (“ESG”) issues. The Adviser selects securities for the Fund that it anticipates will produce a portfolio with less volatility with more capital protection and consistent returns. While the Adviser attempts to manage the Fund’s volatility, there is no guarantee that the strategy will be successful or that the Fund’s portfolio will not experience periods of volatility.

The Fund may sell a stock if the Adviser identifies fundamental, ESG, or legal risks and/or if the risk/return ranking declines due to increasing risk and/or decreasing return potential. The Fund may also decrease weight in an investment for risk control purposes.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Loss of money is a risk of investing in the Fund. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

■ Common Stock Risk. Investments in common stocks are subject to market, economic and business risks that will cause their price to fluctuate over time. Therefore, an investment in the Fund may be more suitable for long-term investors who can bear the risk of these fluctuations.

■ Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

■ Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

■ Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

■ Environmental, Social and Governance Investing Risk. ESG investing risk is the risk stemming from the environmental, social and governance factors that the Fund applies in selecting securities. The Fund intends to invest in companies with measurable high ESG ratings relative to their sector peers, and screen out particular companies that do not meet its ESG criteria. This may affect the Fund’s exposure to certain companies or industries and cause the Fund to forego certain investment opportunities. The Fund’s results may be lower than other funds that do not seek to invest in companies based on ESG ratings and/or screen out certain companies or industries. The Fund seeks to identify companies that it believes may have a societal impact outcome, but investors may differ in their views of what constitutes positive or negative societal impact outcomes. As a result, the Fund may invest in companies that do not reflect the beliefs and values of any particular investor.

■ Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

■ Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

■ High Portfolio Turnover Risk. The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions and cause higher levels of current tax liability to shareholders of the Fund. A portfolio turnover rate of 100% is considered to be high. For the last fiscal year, the annual portfolio turnover rate of the Fund was lower than 100%, but the Fund’s portfolio turnover rate is expected to vary from year to year. The Adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

■ Investment Companies and ETFs Risk. Investing in other investment companies, including ETFs, may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. The risk of owning an investment company or ETF generally reflects the risks of owning the underlying investments the investment company or ETF holds. The Fund may incur brokerage fees in connection with its purchase of ETF shares. Certain ETFs maybe thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

■ Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium- capitalization stocks.

■ Low Volatility Risk. Although subject to the risks of common stocks, low volatility stocks are seen as having a lower risk profile than the overall markets. However, a portfolio comprised of low volatility stocks may not produce investment exposure that has lower variability to changes in such stocks’ price levels. Investing in low volatility stocks may limit the Fund’s gains in rising markets.

■ Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

■ Market Risk. The NAV of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes will produce less volatility, there is no guarantee that the stocks will perform as expected.

■ Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

■ Opportunity Risk. As with all mutual funds, the Fund is subject to the risk of missing out on an opportunity because the assets necessary to take advantage of it are tied up in less advantageous investments.

■ Warrants Risk. The purchase of warrants involves the risk that the Fund could lose the purchase value of a warrant if the right to subscribe to additional shares is not executed prior to the warrant’s expiration. Also, the purchase of warrants involves the risk that the effective price paid for the warrant added to the subscription price of the related security may exceed the value of the subscribed security’s market price such as when there is no movement in the level of the underlying security.

Risk Lose Money [Text]

rr_RiskLoseMoney

Loss of money is a risk of investing in the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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Returns shown were generated under the management of the Fund’s former investment adviser and reflect a previous investment strategy. The Fund operated as a series of Scotia Institutional Funds prior to the close of business on March 21, 2014 (the “Predecessor Fund”). Before the Fund commenced operations, all of the assets and liabilities of the Predecessor Fund were transferred to the Fund in a tax-free reorganization (the “Reorganization”). The Reorganization occurred on March 21, 2014. As a result of the Reorganization, the Fund assumed the performance and accounting history of the Predecessor Fund prior to the date of the Reorganization. The performance shown for periods prior to March 21, 2014 is that of the Predecessor Fund.

The Board approved the Adviser to serve as the Global Equity Fund’s investment adviser effective January 1, 2017. Returns shown for periods prior to January 1, 2017 were generated under the management of the Global Equity Fund’s former investment adviser.

The chart below illustrates the performance of the Fund’s Class I Shares. Performance for Class A Shares and Class C Shares is not shown because Class A Shares and Class C Shares had not commenced operations prior to the date of this Prospectus. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information may be obtained at www.sgiam.com or by calling 855-744-8500.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

Performance for Class A Shares and Class C Shares is not shown because Class A Shares and Class C Shares had not commenced operations prior to the date of this Prospectus.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

855-744-8500

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.sgiam.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the period reflected in the chart above):

Best Quarter: 23.87% (quarter ended September 30, 2013)
Worst Quarter: -16.50% (quarter ended September 30, 2011)

Performance Table Heading

rr_PerformanceTableHeading

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the Fund’s Class I Shares average annual total returns for the periods indicated to the average annual total returns of a broad-based securities market index for the same periods. Past performance (before and after taxes) is not necessarily an indicator of how the Fund will perform in the future.

Summit Global Investments | SGI Global Equity Fund | MSCI ACWI Index (reflects no deductions for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

26.60%

5 Years

rr_AverageAnnualReturnYear05

8.41%

10 Years

rr_AverageAnnualReturnYear10

8.79%

Since Inception

rr_AverageAnnualReturnSinceInception

12.36%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 01, 2009

Summit Global Investments | SGI Global Equity Fund | Class I Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

SGLIX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.41%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.11%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.27%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

0.84%

One Year

rr_ExpenseExampleYear01

$ 8,575

Three Years

rr_ExpenseExampleYear03

32,606

Five Years

rr_ExpenseExampleYear05

58,544

Ten Years

rr_ExpenseExampleYear10

$ 132,750

Annual Return 2010

rr_AnnualReturn2010

50.67%

Annual Return 2011

rr_AnnualReturn2011

4.61%

Annual Return 2012

rr_AnnualReturn2012

6.60%

Annual Return 2013

rr_AnnualReturn2013

42.08%

Annual Return 2014

rr_AnnualReturn2014

5.00%

Annual Return 2015

rr_AnnualReturn2015

9.08%

Annual Return 2016

rr_AnnualReturn2016

(10.31%)

Annual Return 2017

rr_AnnualReturn2017

24.60%

Annual Return 2018

rr_AnnualReturn2018

(2.84%)

Annual Return 2019

rr_AnnualReturn2019

24.02%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2013

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

23.87%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(16.50%)

1 Year

rr_AverageAnnualReturnYear01

24.02%

5 Years

rr_AverageAnnualReturnYear05

7.99%

10 Years

rr_AverageAnnualReturnYear10

13.92%

Since Inception

rr_AverageAnnualReturnSinceInception

16.62%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 01, 2009

Summit Global Investments | SGI Global Equity Fund | Class I Shares | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

23.17%

^[4]

5 Years

rr_AverageAnnualReturnYear05

7.34%

^[4]

10 Years

rr_AverageAnnualReturnYear10

12.75%

^[4]

Since Inception

rr_AverageAnnualReturnSinceInception

15.07%

^[1],[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 01, 2009

^[4]

Summit Global Investments | SGI Global Equity Fund | Class I Shares | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

15.09%

5 Years

rr_AverageAnnualReturnYear05

6.17%

10 Years

rr_AverageAnnualReturnYear10

11.22%

Since Inception

rr_AverageAnnualReturnSinceInception

13.46%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 01, 2009

Summit Global Investments | SGI Global Equity Fund | Class A Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

SGLAX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.25%

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[5]

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.41%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.36%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.27%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.09%

One Year

rr_ExpenseExampleYear01

$ 630

Three Years

rr_ExpenseExampleYear03

908

Five Years

rr_ExpenseExampleYear05

1,206

Ten Years

rr_ExpenseExampleYear10

$ 2,052

Summit Global Investments | SGI Global Equity Fund | Class C Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

SGLOX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses

rr_OtherExpensesOverAssets

0.41%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.11%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.27%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.84%

One Year

rr_ExpenseExampleYear01

$ 187

Three Years

rr_ExpenseExampleYear03

635

Five Years

rr_ExpenseExampleYear05

1,109

Ten Years

rr_ExpenseExampleYear10

$ 2,420

[1] While the Predecessor Fund commenced operations on March 31, 2009, the Predecessor Fund began investing consistent with its investment objective on April 1, 2009.

[2] "Other Expenses" for Class A Shares and Class C Shares, which had not commenced operations as of the date of this prospectus, are estimated based on Class I Shares for the current fiscal year.

[3] Summit Global Investments, LLC (the "Adviser"), the Fund's investment adviser, has contractually agreed to waive management fees and reimburse expenses through February 28, 2021 to the extent that Total Annual Fund Operating Expenses (excluding certain items discussed below) exceed 0.84%, 1.09%, and 1.84% of the Fund's average daily net assets attributable to Class I Shares, Class A and Class C Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and are expected to cause net Total Annual Fund Operating Expenses to exceed 0.84%,1.09% or 1.84%, as applicable: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation may not be terminated before February 28, 2021 without the approval of the Board of Directors of The RBB Fund, Inc. (the "Company"). If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 0.84%, 1.09% and 1.84%, of the Fund's average daily net assets attributable to Class I Shares, Class A Shares and Class C Shares, respectively, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").

[5] A contingent deferred sales charge of 1.00% is assessed on certain redemptions of Class A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Institutional Class Prospectus | Boston Partners All-Cap Value Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — BOSTON PARTNERS ALL-CAP VALUE FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

Current income is a secondary objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 33% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

33.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers across the capitalization spectrum and identified by the Adviser as having value characteristics.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals, such as return on equity and earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may also invest up to 20% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

The Fund may invest up to 10% of its net assets in securities that can be converted into common stock, such as certain debt securities and preferred stock.

The Fund may hedge overall portfolio exposure up to 40% of its net assets through the purchase and sale of index and individual put and call options.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may “cover” a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the long-term performance of the Boston Partners All-Cap Value Fund’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	13.23% (quarter ended December 31, 2011)
Worst Quarter:	-17.49% (quarter ended September 30, 2011)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Institutional Class Prospectus | Boston Partners All-Cap Value Fund | Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

26.26%

5 Years

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8.20%

10 Years

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11.71%

Institutional Class Prospectus | Boston Partners All-Cap Value Fund | Institutional Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

BPAIX

Management Fees

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0.70%

Distribution and/or Service (12b-1) Fees

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none

Other Expenses

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0.12%

Acquired fund fees and expenses

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0.01%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.83%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.03%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

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0.80%

One Year

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$ 817

Three Years

rr_ExpenseExampleYear03

2,619

Five Years

rr_ExpenseExampleYear05

4,575

Ten Years

rr_ExpenseExampleYear10

$ 10,226

Annual Return 2010

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13.42%

Annual Return 2011

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(1.38%)

Annual Return 2012

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15.83%

Annual Return 2013

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39.12%

Annual Return 2014

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12.23%

Annual Return 2015

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0.95%

Annual Return 2016

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14.82%

Annual Return 2017

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17.87%

Annual Return 2018

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(11.87%)

Annual Return 2019

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27.88%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Dec. 31, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.23%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(17.49%)

1 Year

rr_AverageAnnualReturnYear01

27.88%

5 Years

rr_AverageAnnualReturnYear05

9.02%

10 Years

rr_AverageAnnualReturnYear10

12.03%

Institutional Class Prospectus | Boston Partners All-Cap Value Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

27.09%

^[3]

5 Years

rr_AverageAnnualReturnYear05

7.82%

^[3]

10 Years

rr_AverageAnnualReturnYear10

10.94%

^[3]

Institutional Class Prospectus | Boston Partners All-Cap Value Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

17.05%

5 Years

rr_AverageAnnualReturnYear05

6.92%

10 Years

rr_AverageAnnualReturnYear10

9.76%

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 0.80% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.80%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 0.80% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Document and Entity Information	Total
Risk/Return:
Document Type	485BPOS
Document Period End Date	Aug. 31, 2019
Entity Registrant Name	RBB FUND, INC.
Entity Central Index Key	0000831114
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Feb. 28, 2020
Document Effective Date	Feb. 28, 2020
Prospectus Date	Feb. 28, 2020

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND

Prospectus [Line Items]

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Risk/Return [Heading]

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SUMMARY SECTION

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The investment objective of the Abbey Capital Multi Asset Fund (the “Fund”) is to seek long-term capital appreciation.

Objective, Secondary [Text Block]

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Current income is a secondary objective.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund (the “Shares”). You may qualify for sales charge discounts if you invest, or agree to invest in the future, at least $25,000 in Class A Shares of the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information – Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information – Reducing or Eliminating the Front-End Sales Charge.” Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 0% of the average value of its portfolio. In accordance with industry practice, derivative instruments and instruments with a maturity of one year or less at the time of acquisition are excluded from the calculation of the portfolio turnover rate, which leads to the 0% portfolio turnover rate reported above. If those instruments were included in the calculation, the Fund would have a higher portfolio turnover rate.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

none

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you invest, or agree to invest in the future, at least $25,000 in Class A Shares of the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 25,000

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other Expenses" for Class A Shares and Class C Shares, which had not commenced operations as of the date of this Prospectus, are based on Class I Shares for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in Class A and Class C Shares, and $1,000,000 in Class I Shares, of the Fund for the time periods indicated and then redeem all of your Shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same (taking into account the contractual expense limitation until its expiration). Although your actual costs may be higher or lower, based on these assumptions your costs of investing in the Fund would be:

Expense Example, No Redemption Narrative [Text Block]

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You would pay the following expenses on Class C Shares if you did not redeem your shares at the end of the period:

Strategy [Heading]

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Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund seeks to achieve its investment objective by allocating its assets among a “Managed Futures” strategy, a “Long U.S. Equity” strategy and a “Fixed Income” strategy.

The Managed Futures strategy will be achieved by the Fund investing in managed futures investments, including (i) options, (ii) futures, (iii) forwards, (iv) spot contracts, or (v) swaps, including total return swaps, each of which may be tied to (i) commodities, (ii) financial indices and instruments, (iii) foreign currencies, or (iv) equity indices (the “Futures Portfolio”). The Fund may make some or all of its investments in the Futures Portfolio through Abbey Capital Multi Asset Offshore Fund Limited, a wholly-owned and controlled subsidiary of the Fund organized under the laws of the Cayman Islands (the “Subsidiary”), and may invest up to 25% of its total assets in the Subsidiary. The Adviser may allocate assets of the Subsidiary to a single Managed Futures portfolio or multiple Managed Futures portfolios that include investment styles or sub-strategies such as (i) trend following, (ii) discretionary, fundamentals-based investing with a focus on macroeconomic analysis, (iii) strategies that pursue both fundamental and technical trading approaches, (iv) other specialized approaches to specific or individual market sectors such as equities, interest rates, metals, agricultural and soft commodities, and (v) systematic trading strategies which incorporate technical and fundamental variables.

The Managed Futures strategy investments are designed to achieve capital appreciation in the financial and commodities futures markets. The Adviser intends to allocate a portion of the assets of the Fund and the Subsidiary to one or more Trading Advisers to manage in percentages determined at the discretion of the Adviser. Each current Trading Adviser is registered with the U.S. Commodity Futures Trading Commission (the “CFTC”) as a Commodity Trading Advisor (“CTA”). Trading Advisers that are not registered with the SEC as investment advisers provide advice only regarding matters that do not involve securities. The trading strategies employ several different trading styles using different research and trading methodologies, in a wide range of global financial and commodity markets operating over multiple time frames. Trading Advisers may use discretionary approaches aimed at identifying value investments and turning points in trends. The Fund invests in U.S. and non-U.S. markets and in developed and emerging markets.

The Long U.S. Equity strategy will be achieved by the Adviser targeting an allocation of approximately 50% of the Fund’s total assets in a portfolio of one or more U.S. equity index futures (the “Equity Portfolio”). The Adviser will monitor the percentage of the Fund’s total assets that form the Equity Portfolio on a daily basis. The Adviser will establish ‘rebalancing thresholds’ so that if at any time the percentage of the Fund’s total assets invested in the Equity Portfolio is above or below the target allocation of approximately 50% by a specific amount, then the Adviser will seek to rebalance the Equity Portfolio back towards its target allocation of approximately 50%. Such rebalancing thresholds will be determined by the Adviser and may be subject to change from time to time.

As part of the Long U.S. Equity strategy, the Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, futures, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, and shares of other investment companies (including exchanged-traded funds (“ETFs”)) and real estate investment trusts (“REITs”). The Fund may also participate as a purchaser in initial public offerings of securities (“IPO”), a company’s first offering of stock to the public. The Fund defines United States companies as companies (i) that are organized under the laws of the United States; (ii) whose principal trading market is in a the United States; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, within the United States.

The Fixed Income strategy invests the Fund’s assets primarily in investment grade fixed income securities (of all durations and maturities) in order to generate interest income and capital appreciation, which may add diversification to the returns generated by the Fund’s Managed Futures and Long U.S. Equity strategies. The level of the Fund’s assets invested in the Fixed Income Strategy will be managed and rebalanced pursuant to thresholds determined by the Adviser, which may be subject to change from time to time. In line with these thresholds, any proceeds of maturing fixed income securities will be substantially reinvested into additional fixed income securities. The Fund must set aside liquid assets to “cover” open positions with respect to its managed futures investments. The Fixed Income strategy investments may be used to help cover the Fund’s derivative positions. The Subsidiary may also cover written options with offsetting purchased options in the same commodity and maturity, or by the purchase or sale of the underlying commodity future, in an amount great than or equal to that required by an exercised option.

To achieve its investment objective, the Fund’s Adviser will target approximately 100% exposure of the Fund’s net assets to Managed Futures strategy investments and approximately 50% exposure of the Fund’s net assets to Long U.S. Equity strategy investments. The Fund’s remaining net assets will be allocated to the Fixed Income strategy investments.

As much of the trading within the Fund is in futures markets, the Fund is likely to have cash balances surplus to margin requirements. The cash portfolio will be invested on a short-term, highly liquid, basis, to meet margin calls on the futures positions.

The Fund is “non-diversified” for purposes of the Investment Company Act of 1940, as amended, (the “1940 Act”), which means that the Fund may invest in fewer securities at any one time than a diversified fund. The Fund may not invest more than 15% of its net assets in illiquid securities. The Fund’s investments in certain derivative instruments and its short selling activities involve the use of leverage.

Generally, the Subsidiary will invest primarily in commodity futures, but it may also invest in financial futures, option and swap contracts, fixed income securities, pooled investment vehicles, including those that are not registered pursuant to the 1940 Act and other investments intended to serve as margin or collateral for the Subsidiary’s derivative positions. The Fund invests in the Subsidiary in order to gain exposure to the commodities markets within the limitations of the federal tax laws, rules and regulations that apply to regulated investment companies. Unlike the Fund, the Subsidiary may invest without limitation in commodity-linked derivatives, however, the Subsidiary will comply with the same 1940 Act asset coverage requirements with respect to its investments in commodity-linked derivatives that are applicable to the Fund’s transactions in derivatives. In addition, to the extent applicable to the investment activities of the Subsidiary, the Subsidiary will be subject to the same fundamental investment restrictions and will follow the same compliance policies and procedures as the Fund. Unlike the Fund, the Subsidiary will not seek to qualify as a regulated investment company (“RIC”) under Subchapter M of Subtitle A, Chapter 1, of the Internal Revenue Code of 1986, as amended (the “Code”). The Fund is the sole shareholder of the Subsidiary and does not expect shares of the Subsidiary to be offered or sold to other investors.

Risk [Heading]

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Principal Investment Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

The principal risk factors affecting shareholders’ investments in the Fund (and, indirectly, in the Subsidiary) are set forth below.

● Commodity Sector Risk: Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative instruments may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments. The prices of energy, industrial metals, precious metals, agriculture and livestock sector commodities may fluctuate widely due to factors such as changes in value, supply and demand and governmental regulatory policies. The commodity-linked securities in which the Fund invests may be issued by companies in the financial services sector, and events affecting the financial services sector may cause the Fund’s Share value to fluctuate.

● Counterparty Risk: Counterparty risk is the risk that the other party(s) to an agreement or a participant to a transaction, such as a broker or the futures commission merchant, might default on a contract or fail to perform by failing to pay amounts due or failing to fulfill the obligations of the contract or transaction.

● Credit Risk: Credit risk refers to the possibility that the issuer of the security will not be able to make principal and interest payments when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. Securities rated in the four highest categories by the rating agencies are considered investment grade but they may also have some speculative characteristics. Investment grade ratings do not guarantee that bonds will not lose value.

● Currency Risk: Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls. Forward foreign currency exchange contracts may limit potential gains from a favorable change in value between the U.S. dollar and foreign currencies. Unanticipated changes in currency pricing may result in poorer overall performance for the Fund than if it had not engaged in these contracts.

● Cyber Security Risk: Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk: The Fund’s investments in derivative instruments including options, forward currency exchange contracts, swaps and futures, which may be leveraged, may result in losses. Investments in derivative instruments may result in losses exceeding the amounts invested.

● Emerging Markets Risk: Investment in emerging market securities involves greater risk than that associated with investment in foreign securities of developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Equity and Equity-Related Securities Risk: Investments in equity securities and equity derivatives in general are subject to market risks that may cause their prices to fluctuate over time. The value of a convertible security may not increase or decrease as rapidly as the underlying common stock. Common stocks may decline over short or even extended periods of time. The purchase of rights or warrants involves the risk that the Fund could lose the purchase value of a right or warrant if the right to subscribe to additional shares is not executed prior to the right’s or warrant’s expiration. The value of securities convertible into equity securities, such as warrants or convertible debt, is also affected by prevailing interest rates, the credit quality of the issuer and any call provision.

● Fixed Income Securities Risk: Fixed income securities in which the Fund may invest are subject to certain risks, including: interest rate risk, prepayment risk and credit/default risk. Interest rate risk involves the risk that prices of fixed income securities will rise and fall in response to interest rate changes. Prepayment risk involves the risk that in declining interest rate environments prepayments of principal could increase and require the Fund to reinvest proceeds of the prepayments at lower interest rates. Credit risk involves the risk that the credit rating of a security may be lowered.

● Foreign Investments Risk: International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through “sponsored” or “unsponsored” facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders.

● Forward and Futures Risk: The successful use of forward and futures contracts draws upon the Adviser’s and Trading Advisers’ skill and experience with respect to such instruments and are subject to special risk considerations. The primary risks associated with the use of futures contracts are (a) the imperfect correlation between the change in market value of instruments held by the Fund and the price of the forward or futures contract; (b) possible lack of a liquid secondary market, and possible regulatory position limits and restrictions, for a forward or futures contract and the resulting inability to close a forward or futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s and Trading Advisers’ inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; (e) the possibility that the counterparty will default in the performance of its obligations; and (f) if the Fund has insufficient cash, it may have to sell securities from its portfolio to meet daily variation margin requirements, and the Fund may have to sell securities at a time when it may be disadvantageous to do so.

● Hedging Transactions Risk: The Adviser and Trading Advisers from time to time employ various hedging techniques. The success of the Fund’s hedging strategy will be subject to the Adviser’s and Trading Advisers’ ability to correctly assess the degree of correlation between the performance of the instruments used in the hedging strategy and the performance of the investments in the portfolio being hedged. Since the characteristics of many securities change as markets change or time passes, the success of the Fund’s hedging strategy will also be subject to the Adviser’s and Trading Advisers’ ability to continually recalculate, readjust, and execute hedges in an efficient and timely manner. For a variety of reasons, the Adviser and Trading Advisers may not seek to establish a perfect correlation between such hedging instruments and the portfolio holdings being hedged. Such imperfect correlation may prevent the Fund from achieving the intended hedge or expose the Fund to risk of loss. In addition, it is not possible to hedge fully or perfectly against any risk, and hedging entails its own cost.

● High Portfolio Turnover Risk: The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions, and cause higher levels of current tax liability to shareholders in the Fund.

● Interest Rate Risk: Interest rate risk is the risk that prices of fixed income securities generally increase when interest rates decline and decrease when interest rates increase. The Fund may lose money if short term or long term interest rates rise sharply or otherwise change in a manner not anticipated by the Adviser and Trading Advisers. It is likely there will be less governmental action in the near future to maintain low interest rates. The negative impact on fixed income securities from the resulting rate increases for that and other reasons could be swift and significant.

● Leveraging Risk: Investments in derivative instruments may give rise to a form of leverage. Trading Advisers may engage in speculative transactions which involve substantial risk and leverage, such as making short sales. The use of leverage by the Adviser and Trading Advisers may increase the volatility of the Fund. These leveraged instruments may result in losses to the Fund or may adversely affect the Fund’s net asset value (“NAV”) or total return, because instruments that contain leverage are more sensitive to changes in interest rates. The Fund may also have to sell assets at inopportune times to satisfy its obligations in connection with such transactions.

● Limiting Operating History Risk: The Fund has a limited operating history. There is a risk that the Fund will not grow or maintain an economically viable size, in which case the Board may determine to liquidate the Fund.

● Management Risk: The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Manager Risk: If the Adviser and Trading Advisers make poor investment decisions, it will negatively affect the Fund’s investment performance.

● Market Risk: The NAV of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money.

● Multi-Manager Dependence Risk: The success of the Fund’s investment strategy depends both on the Adviser’s ability to select Trading Advisers and to allocate assets to those Trading Advisers and on each Trading Adviser’s ability to execute the relevant strategy and select investments for the Fund and the Subsidiary. The Trading Advisers’ investment styles may not always be complementary, which could adversely affect the performance of the Fund.

● New Adviser Risk: The Trading Advisers may be newly registered or not registered with the SEC and/or have not previously managed a mutual fund. Accordingly, investors in the Fund bear the risk that a Trading Adviser’s inexperience may limit its effectiveness.

● Non-Diversification Risk: The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk: Purchasing and writing put and call options are highly specialized activities and entail greater than ordinary investment risks. The Fund may not fully benefit from or may lose money on an option if changes in its value do not correspond as anticipated to changes in the value of the underlying securities.

● Quantitative Trading Strategies Risk: The Adviser and Trading Advisers may use quantitative methods to select investments. Securities or other investments selected using quantitative methods may perform differently from the market as a whole or from their expected performance for many reasons, including factors used in building the quantitative analytical framework, the weights placed on each factor, and changing sources of market returns, among others. Any errors or imperfections in quantitative analyses or models, or in the data on which they are based, could adversely affect the ability of the Adviser or a Trading Adviser to use such analyses or models effectively, which in turn could adversely affect the Fund’s performance. There can be no assurance that these methodologies will help the Fund to achieve its investment objective.

● Subsidiary Risk: By investing in the Subsidiary, the Fund is indirectly exposed to the risks associated with the Subsidiary’s investments. The derivatives and other investments held by the Subsidiary are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the fund. The Subsidiary is not registered under the 1940 Act, and, unless otherwise noted in this Prospectus, is not subject to all the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to continue to operate as it does currently and could adversely affect the Fund.

● Tax Risk: In order to qualify as a RIC, the Fund must meet certain requirements regarding the source of its income, the diversification of its assets and the distribution of its income. Under the test regarding the source of a RIC’s income, at least 90% of the gross income of the RIC each year must be qualifying income, which consists of dividends, interest, gains on investment assets and other categories of investment income. In 2006, the Internal Revenue Service (“IRS”) published a ruling that income realized from swaps with respect to a commodities index would not be qualifying income. The Fund’s investment in the Subsidiary is expected to provide the Fund with exposure to the commodities markets within the limitations of the Code for qualification as a RIC, but there is a risk that the IRS could assert that the income derived from the Fund’s investment in the Subsidiary and certain commodity-linked structured notes will not be considered qualifying income for purposes of the Fund remaining qualified as a RIC for U.S. federal income tax purposes. If the Fund were to fail to qualify as a RIC and became subject to federal income tax, shareholders of the Fund would be subject to diminished returns. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or its Subsidiary to operate as described in this Prospectus and the SAI and could adversely affect the Fund. For example, the Cayman Islands does not currently impose any income, corporate or capital gains tax or withholding tax on the Subsidiary. If Cayman Islands law changes such that the Subsidiary must pay Cayman Islands taxes, Fund shareholders would likely suffer decreased investment returns.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Fund. The bar chart below shows how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of all dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Updated performance information is available online at www.abbeycapital.com or by calling 1-844-261-6484 (toll free).

The Fund commenced operations as a series of the Company on April 11, 2018, when all of the assets of Abbey Global LP (the “Predecessor Fund”) transferred to Class I Shares of the Fund. The Fund’s objectives, policies, guidelines and restrictions are in all material respects equivalent to the Predecessor Fund. Accordingly, the performance information shown below for periods prior to April 11, 2018 is that of the Predecessor Fund. The Predecessor Fund was not registered under the 1940 Act, and thus was not subject to certain investment and operational restrictions that are imposed by the 1940 Act. If the Predecessor Fund had been registered under the 1940 Act, its performance may have been adversely affected. Accordingly, future Fund performance may be different than the Predecessor Fund’s restated past performance. The Predecessor Fund was not a regulated investment company under Subchapter M of the Internal Revenue Code and therefore did not distribute current or accumulated earnings and profits and was not subject to the diversification and source of income requirements applicable to regulated investment companies. Monthly returns since the inception of the Predecessor Fund are provided in Appendix A of the Prospectus.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of all dividends and distributions.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-844-261-6484

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.abbeycapital.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Year s Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the period shown in the chart, the highest quarterly return was 17.10% (for the quarter ended September 30, 2010) and the lowest quarterly return was -15.91% (for the quarter ended September 30, 2011).

Performance Table Heading

rr_PerformanceTableHeading

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The following table compares the average annual total returns for the Fund’s Class I shares, including the Predecessor Fund, before and after taxes for the past calendar year, five-year, ten-year and since inception periods to the average annual total returns of a broad-based securities market index for the same periods. Average annual returns for Class A Shares and Class C Shares of the Fund are not included because they had not commenced operations prior to the date of this Prospectus.

Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND | S&P 500® Total Return Index (reflects no deduction for fees, expenses and taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

31.49%

5 Years

rr_AverageAnnualReturnYear05

11.70%

10 Years

rr_AverageAnnualReturnYear10

13.56%

Since Inception

rr_AverageAnnualReturnSinceInception

8.50%

Inception Date

rr_AverageAnnualReturnInceptionDate

May 14, 2002

Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND | CLASS I SHARES

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

MAFIX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

1.77%

^[1]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.50%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.27%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.48%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.79%

One Year

rr_ExpenseExampleYear01

$ 18,187

Three Years

rr_ExpenseExampleYear03

66,333

Five Years

rr_ExpenseExampleYear05

117,142

Ten Years

rr_ExpenseExampleYear10

$ 256,813

Annual Return 2010

rr_AnnualReturn2010

18.65%

Annual Return 2011

rr_AnnualReturn2011

(9.19%)

Annual Return 2012

rr_AnnualReturn2012

13.68%

Annual Return 2013

rr_AnnualReturn2013

27.68%

Annual Return 2014

rr_AnnualReturn2014

22.24%

Annual Return 2015

rr_AnnualReturn2015

(0.60%)

Annual Return 2016

rr_AnnualReturn2016

5.58%

Annual Return 2017

rr_AnnualReturn2017

12.31%

Annual Return 2018

rr_AnnualReturn2018

(6.46%)

Annual Return 2019

rr_AnnualReturn2019

21.64%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

highest quarterly return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.10%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

lowest quarterly return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(15.91%)

1 Year

rr_AverageAnnualReturnYear01

21.64%

5 Years

rr_AverageAnnualReturnYear05

6.04%

10 Years

rr_AverageAnnualReturnYear10

9.87%

Since Inception

rr_AverageAnnualReturnSinceInception

10.12%

Inception Date

rr_AverageAnnualReturnInceptionDate

May 14, 2002

Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND | CLASS I SHARES | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

16.33%

^[3]

5 Years

rr_AverageAnnualReturnYear05

4.47%

^[3]

10 Years

rr_AverageAnnualReturnYear10

9.05%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

9.66%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 14, 2002

^[3]

Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND | CLASS I SHARES | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

12.98%

^[3]

5 Years

rr_AverageAnnualReturnYear05

4.08%

^[3]

10 Years

rr_AverageAnnualReturnYear10

7.79%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

8.56%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 14, 2002

^[3]

Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND | CLASS A SHARES

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

MAFAX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.75%

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[4]

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

1.77%

^[1]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.50%

^[5]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.52%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.48%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.04%

One Year

rr_ExpenseExampleYear01

$ 770

Three Years

rr_ExpenseExampleYear03

1,271

Five Years

rr_ExpenseExampleYear05

1,798

Ten Years

rr_ExpenseExampleYear10

$ 3,233

Abbey Capital | ABBEY CAPITAL MULTI ASSET FUND | CLASS C SHARES

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

MAFCX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[6]

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

1.77%

^[1]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses

rr_OtherExpensesOverAssets

0.50%

^[5]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

3.27%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.48%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.79%

One Year

rr_ExpenseExampleYear01

$ 382

Three Years

rr_ExpenseExampleYear03

962

Five Years

rr_ExpenseExampleYear05

1,666

Ten Years

rr_ExpenseExampleYear10

3,535

One Year

rr_ExpenseExampleNoRedemptionYear01

282

Three Years

rr_ExpenseExampleNoRedemptionYear03

962

Five Years

rr_ExpenseExampleNoRedemptionYear05

1,666

Ten Years

rr_ExpenseExampleNoRedemptionYear10

$ 3,535

[1] Management Fees include advisory fees paid to both Abbey Capital Limited (the "Adviser") and one or more trading advisers (the "Trading Advisers"). There are no performance fees charged by the Adviser or Trading Advisers either at the Fund or at the Fund's wholly-owned Subsidiary.

[2] The Adviser has contractually agreed to waive its advisory fee and/or reimburse expenses in order to limit Total Annual Fund Operating Expenses (excluding certain items discussed below) to 1.79%, 2.04% and 2.79% of the Fund's average daily net assets attributable to Class I Shares, Class A Shares and Class C Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total Annual Fund Operating Expenses to exceed 1.79%, 2.04% or 2.79%, as applicable: acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 for Class I Shares, Class A Shares and Class C Shares, and may not be terminated prior to that date without the approval of the Board of Directors of The RBB Fund, Inc. (the "Company"). If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.79%, 2.04% and 2.79%, as applicable, the Adviser may recoup any waived or reimbursed amounts from the Fund within three years from the date on which such waiver or reimbursement was made by the Adviser, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[3] After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[4] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Class A Shares made within 12 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[5] "Other Expenses" for Class A Shares and Class C Shares, which had not commenced operations as of the date of this Prospectus, are based on Class I Shares for the current fiscal year.

[6] The CDSC applies to redemptions of Class C Shares made within 12 months of purchase and will be assessed on an amount equal to the lesser of the offering price at the time of purchase of the shares redeemed and the net asset value of the shares redeemed at the time of redemption.

XML

Total

Matson Money | Matson Money International Equity VI Portfolio

MATSON MONEY INTERNATIONAL EQUITY VI PORTFOLIO FMVIX

Investment Objective

The Matson Money International Equity VI Portfolio (for this section only, the “Portfolio”) seeks long-term capital appreciation.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Portfolio. This table does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, overall fees and expenses would be higher.

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Matson Money Matson Money International Equity VI Portfolio Institutional Class
Management Fees	0.50%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.36%
Acquired fund fees and expenses	0.43%	[1]
Total Annual Fund Operating Expenses	1.29%

Example

This Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. This Example does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, the costs shown below would be higher.

The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Matson Money | Matson Money International Equity VI Portfolio | Institutional Class | USD ($)	132	410	710	1,561

Portfolio Turnover

The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Portfolio shares are held in a taxable account. These costs, which are not reflected in Total Annual Portfolio Operating Expenses or in the Example, affect the Portfolio’s performance. During the fiscal year ended August 31, 2019, the Portfolio’s portfolio turnover rate was 13% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Portfolio pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in equity securities, such as common stocks, preferred stocks or securities convertible into stocks, of foreign companies, or invest substantially all of their assets in such equity securities. The Portfolio will diversify its investments by investing primarily in investment companies that focus on different segments of the foreign equity markets, including emerging markets, with little or no focus on domestic equity markets. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Portfolio’s net assets to be invested in the securities of investment companies, including other investment companies funded by insurance company separate accounts, that invest in the types of securities described in each asset class below, with less than 5% of the net assets invested in cash or money market instruments.

International Small Cap Value Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of small companies in foreign countries with developed markets that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios, as well as economic conditions and developments in the issuer’s industry. The criteria used for assessing value are subject to change from time to time. The underlying investment adviser(s) determine the maximum market capitalization of a small company with respect to each country. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Large Cap Value Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of large companies in foreign countries with developed markets that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios, as well as economic conditions and developments in the issuer’s industry. The criteria used for assessing value are subject to change from time to time. The underlying investment adviser(s) determine the minimum market capitalization of a large company with respect to each country or region. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Small Company Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of small companies in foreign countries with developed markets. The underlying investment adviser(s) determine the maximum market capitalization of a small company with respect to each country. This threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Large Cap Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of large companies in foreign countries with developed markets. The underlying investment adviser(s) determine the minimum market capitalization of a large company with respect to each country or region. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

Emerging Markets Asset Class, Emerging Markets Value Asset Class, and Emerging Markets Small Cap Asset Class (collectively, the “Emerging Markets Asset Classes”): Underlying investment companies comprising each Emerging Markets Asset Class generally will purchase stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of companies located in emerging market countries, including frontier markets (emerging market countries in an earlier stage of development). The underlying investment companies investing in securities of the Emerging Markets Asset Class and the Emerging Markets Small Cap Asset Class will generally purchase the equity securities of larger and smaller companies, respectively, within each country. The underlying investment adviser(s) determine company size primarily based on market capitalization. The thresholds will vary by country or region, and the dollar amounts will change from time to time due to market conditions.

The underlying investment companies in the Emerging Markets Value Asset Class generally will purchase emerging market equity securities that are deemed by the underlying investment adviser(s) to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time.

The underlying investment companies may use derivatives, such as futures contracts and options on futures contracts for equity securities and indices, to hedge currency exposure or to adjust market exposure based on actual or expected cash inflows or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, forward currency contracts, options and swaps to help the ETF track its underlying index.

The Portfolio reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Portfolio employs a temporary defensive measure, the Portfolio may not achieve its investment objective. Periodically the Adviser will review the allocations for the Portfolio in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Portfolio in the underlying investment companies without notice to shareholders or the holders of the variable annuity or variable life insurance policies.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Portfolio, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Portfolio, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● The value of particular foreign equity securities which the Portfolio’s underlying investment companies may purchase or foreign stock markets on which the securities they may purchase are traded may decline in value.

● Stocks of large cap or small cap foreign companies in which the Portfolio’s underlying investment companies may invest may temporarily fall out of favor with investors or may be more volatile than particular foreign stock markets or foreign stock markets as a whole.

● The smaller the capitalization of a company, generally the less liquid its stock and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records and are more likely to fail than companies with larger market capitalizations.

● Stocks of large cap or small cap foreign companies in which the Portfolio’s underlying investment companies may invest may suffer unexpected losses or lower than expected earnings or such securities may become difficult or impossible to sell at the time and for the price the underlying investment advisers would like.

● Because the Portfolio owns shares of underlying investment companies that invest in foreign issuers, the Portfolio is subject to risks presented by investments in such issuers. Securities of foreign issuers may be negatively affected by political events, economic conditions, or inefficient, illiquid or unregulated markets in foreign countries. Foreign issuers may be subject to inadequate regulatory or accounting standards.

● Investments in emerging market securities by underlying investment companies in which the Portfolio invests are subject to higher risks than those in developed market countries because there is greater uncertainty in less established markets and economics. The foregoing risks may be greater in frontier markets, which are among the smallest and least mature investment markets.

● Currency risk is the risk that exchange rates for currencies in which securities held by the underlying investment companies in which the Portfolio invests are denominated will fluctuate daily. In general, the underlying investment companies do not hedge currency risk. As a result, if currencies in which foreign holdings are denominated depreciate against the U.S. Dollar, the value of your investment in the Portfolio may be adversely affected.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Portfolio could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Portfolio invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in equity securities of foreign companies, the NAV of the Portfolio will change with changes in the share prices of the investment companies in which the Portfolio invests.

● There is a risk that the Portfolio, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Portfolio will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. the Portfolio may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Cyber security risk is the risk of an unauthorized breach and access to Portfolio assets, Portfolio or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Portfolio, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Portfolio investors from purchasing, redeeming or exchanging shares or receiving distributions. The Portfolio and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Portfolio or its service providers may adversely impact and cause financial losses to the Portfolio or its shareholders.

More information about the Portfolio’s investments and risks is contained under the section entitled “More About Each Portfolio’s Investments and Risks.”

Performance Information

The chart below illustrates the performance of the Portfolio. The information shows you how the Portfolio’s performance has varied year by year and provides some indication of the risks of investing in the Portfolio. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 9.78% (quarter ended December 31, 2019)

Worst Quarter: -14.64% (quarter ended December 31, 2018)

Average Annual Total Returns for the Periods Ended December 31, 2019

The following table compares the average annual total returns of the Portfolio before and after taxes for the past calendar year, the past five calendar years, and since inception to the average total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Matson Money - Matson Money International Equity VI Portfolio		1 Year	5 Years	Since Inception	Inception Date
Institutional Class		17.36%	4.54%	2.53%	Feb. 18, 2014
Institutional Class | After Taxes on Distributions	[1]	16.30%	3.72%	1.80%	Feb. 18, 2014
Institutional Class | After Taxes on Distributions and Sales	[2]	11.27%	3.45%	1.89%	Feb. 18, 2014
MSCI World (excluding U.S.) Index (reflects no deduction for fees, expenses or taxes)		22.49%	5.42%	4.51%	Feb. 18, 2014
Composite Index	[3]	21.10%	6.33%	5.20%	Feb. 18, 2014

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Portfolio incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Portfolio Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] In certain cases, the figure representing "Portfolio Returns After Taxes on Distributions and Sale of Portfolio Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

[3] The Composite Index is comprised of the MSCI EAFE Index, MSCI EAFE Value Index, MSCI EAFE Small Cap Index, and MSCI Emerging Markets Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Portfolio's Investments and Risks."

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Total

Matson Money | Free Market Fixed Income Fund

FREE MARKET FIXED INCOME FUND FMFIX

Investment Objective

The Free Market Fixed Income Fund (for this section only, the “Fund”) seeks total return (consisting of current income and capital appreciation).

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Matson Money Free Market Fixed Income Fund Institutional Class
Management Fees	0.49%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.06%
Acquired fund fees and expenses	0.12%	[1]
Total Annual Fund Operating Expenses	0.67%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Matson Money | Free Market Fixed Income Fund | Institutional Class | USD ($)	68	214	373	833

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual fund Operating Expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 3% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in fixed income securities that the Adviser believes offer the prospect of providing total return, or invest substantially all of their assets in such fixed income securities. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Fund’s net assets to be invested in the securities of investment companies that invest in the types of securities described in each asset class below, with less than 2% of the net assets invested in cash or money market instruments.

One-Year Fixed Income Asset Class: The underlying investment companies generally will purchase U.S. government obligations, U.S. government agency obligations, dollar-denominated obligations of foreign issuers issued in the U.S., securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the U.S.; foreign government and agency obligations, bank obligations, including the obligations of U.S. subsidiaries and branches of foreign banks, corporate obligations, commercial paper, repurchase agreements, and obligations of supranational organizations such as the World Bank, the European Investment Bank, and the Inter-American Development Bank. Generally, obligations comprising this asset class will mature within one year from the date of settlement, but substantial investments may be made in obligations maturing within two years from the date of settlement when greater returns are available.

Two-Year Global Fixed Income Asset Class: The underlying investment companies generally will purchase obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, corporate debt obligations, bank obligations, commercial paper, repurchase agreements, and other debt obligations of domestic and foreign issuers with maturities of no more than two years. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the underlying investment adviser(s) will focus investment in the longer-term area, otherwise, the underlying investment companies will focus investment in the shorter-term area of the eligible maturity range. Because many of the investments of the underlying investment companies in this asset class will be denominated in foreign currencies, the underlying investment companies may also enter into foreign currency forward contracts to attempt to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another.

Intermediate Government Fixed Income Asset Class: The underlying investment companies generally will purchase debt obligations of the U.S. government and U.S. government agencies. Generally, investment companies in the asset class will purchase securities with maturities of between five and fifteen years, however such investment companies ordinarily will have an average weighted maturity of between three and ten years. The underlying investment companies may invest a portion of their assets in the obligations of foreign governments. Those obligations at the time of purchase must be either rated in the highest rating category of a nationally recognized statistical rating organization or, in the case of any obligation that is unrated, of comparable quality.

Five-Year Global Fixed Income Asset Class: The underlying investment companies generally will purchase obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, corporate debt obligations, bank obligations, commercial paper, repurchase agreements, obligations of other domestic and foreign issuers, securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the United States, and obligations of supranational organizations. Generally, obligations comprising this asset class have a weighted average maturity not exceeding five years. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the underlying investment adviser(s) will focus investment in the longer-term area, otherwise, the underlying investment companies will focus investment in the shorter-term area of the eligible maturity range. Because many of the investments of the underlying investment companies in this asset class will be denominated in foreign currencies, the underlying investment companies may also enter into foreign currency forward contracts to attempt to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another.

Short-Term Corporate Bond Asset Class: The underlying investment companies generally will track the investment results of the ICE BofAML 1-5 Year US Corporate Index, which measures the performance of investment-grade corporate bonds of both U.S. and non- U.S. issuers that are U.S. dollar denominated and publicly issued in the U.S. domestic market and have a remaining maturity of greater than or equal to one year and less than five years.

Intermediate-Term Corporate Bond Asset Class: The underlying investment companies generally will track the investment results of the ICE BofAML 5-10 Year US Corporate Index, which measures the performance of investment-grade corporate bonds of both U.S. and non-U.S. issuers that are U.S. dollar denominated and publicly issued in the U.S. domestic market and have a remaining maturity of greater than or equal to five years and less than ten years.

Inflation Protected Securities Asset Class: The underlying investment companies generally will track the investment results of the Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L), which measures the performance of the inflation-protected public obligations of the U.S. Treasury, commonly known as “TIPS.” TIPS are securities issued by the U.S. Treasury that are designed to provide inflation protection to investors. TIPS are income-generating instruments whose interest and principal payments are adjusted for inflation - a sustained increase in prices that erodes the purchasing power of money. The inflation adjustment, which is typically applied monthly to the principal of the bond, follows a designated inflation index, the consumer price index (“CPI”), and TIPS’ principal payments are adjusted according to changes in the CPI. A fixed coupon rate is applied to the inflation-adjusted principal so that as inflation rises, both the principal value and the interest payments increase.

The underlying investment companies may also use derivatives, such as futures contracts and options on futures contracts for equity securities and indices, to hedge currency exposure or to adjust market exposure based on actual or expected cash inflows or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, forward currency contracts, options and swaps to help the ETF track its underlying index.

Certain underlying investment companies may concentrate their investments (invest more than 25% of its total assets) in obligations of U.S. and foreign banks and bank holding companies when the yield to maturity on eligible portfolio investments in banking securities as a group generally exceeds the yield to maturity on all other eligible portfolio investments as a group generally for a period of five consecutive days when the New York Stock Exchange is open for trading. While the Fund will not concentrate its investments in any one industry, the Fund may be focused on banking sectors under certain circumstances.

The Fund reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Fund employs a temporary defensive measure, the Fund may not achieve its investment objective. Periodically the Adviser will review the allocations for the Fund in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Fund in the underlying investment companies without notice to shareholders.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Fixed income securities in which the Fund’s underlying investment companies may invest are subject to certain risks, including: interest rate risk, reinvestment risk, prepayment and extension risk, credit/default risk, and the risks associated with investing in repurchase agreements.

● Interest rate risk involves the risk that prices of fixed income securities will rise and fall in response to interest rate changes.

● Reinvestment risk involves the risk that proceeds from matured investments may be re-invested at lower interest rates.

● Prepayment risk involves the risk that in declining interest rates environments prepayments of principal could increase and require the Fund to reinvest proceeds of the prepayments at lower interest rates.

● Extension risk involves the risk that prepayments of principal will decrease when interest rates rise resulting in a longer effective maturity of a security.

● Credit risk is the risk that the issuer of a security may be unable to make interest payments and/or repay principal when due. Credit risk also involves the risk that the credit rating of a security may be lowered.

● Repurchase agreement risk involves the risk that the other party to a repurchase agreement will be unable to complete the transaction and the underlying investment company in which the Fund invests may suffer a loss as a result.

● Because the Fund owns shares of underlying investment companies that invest in foreign issuers, the Fund is subject to risks presented by investments in such issuers. Securities of foreign issuers may be negatively affected by political events, economic conditions, or inefficient, illiquid or unregulated markets in foreign countries. Foreign issuers may be subject to inadequate regulatory or accounting standards.

● Currency risk is the risk that exchange rates for currencies in which securities held by the underlying investment companies in which the Fund invests are denominated will fluctuate daily. Forward foreign currency exchange contracts may limit potential gains from a favorable change in value between the U.S. dollar and foreign currencies. Unanticipated changes in currency pricing may result in poorer overall performance for the Fund than if it had not engaged in these contracts.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Inflation protected securities, such as TIPS, generally will fluctuate in response to changes in real interest rates, generally decreasing when real interest rates rise and increasing when real interest rates fall. In addition, interest payments on inflation-protected securities will generally vary up or down along with the rate of inflation. Real interest rates are generally measured as a nominal interest less an inflation rate. As such, investors should be aware that an investment in TIPS over a particular timeframe may decrease in value even in an inflationary environment. There can be no assurance that the inflation index used will accurately measure the real rate of inflation in the prices of goods and services. Because of their inflation adjustment feature, inflation-protected bonds typically have lower yields than conventional fixed-rate bonds.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Fund could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Fund invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in fixed income securities, the NAV of the Fund will change with changes in the share prices of the investment companies in which the Fund invests.

● Not all obligations of U.S. government agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some are backed only by the credit of the issuing agency or instrumentality. Accordingly, there may be some risk of default by the issuer in such cases.

● There is a risk that the Fund, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Fund will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● Banks are very sensitive to changes in money market and general economic conditions. Adverse general economic conditions can cause financial difficulties for a bank’s borrowers and the borrowers’ failure to repay their loans can adversely affect the bank’s financial situation. Banks are subject to extensive regulation and decisions by regulators may limit the loans banks make and the interest rates and fees they charge, which could reduce bank profitability.

● Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

More information about the Fund’s investments and risks is contained under the section entitled “More About Each Fund’s Investments and Risks.”

Performance Information

The chart below illustrates the long-term performance of the Fund. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 1.99% (quarter ended March 31, 2019)

Worst Quarter: -1.44% (quarter ended June 30, 2013)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns of the Fund before and after taxes for the past calendar year, the past five calendar years, and past ten calendar years to the average total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Matson Money - Free Market Fixed Income Fund		1 Year	5 Years	10 Years
Institutional Class		4.78%	1.58%	1.53%
Institutional Class | After Taxes on Distributions	[1]	4.17%	1.06%	1.04%
Institutional Class | After Taxes on Distributions and Sales		2.83%	0.99%	0.99%
FTSE World Government Bond Index 1-5 Years(reflects no deduction for fees, expenses or taxes)		3.86%	1.92%	1.85%
Composite Index	[2]	5.34%	2.04%	2.17%

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] The Composite Index is comprised of the Three-Month Treasury Bill Index, Bloomberg Barclays Intermediate Government Bond Index, ICE BofAML 1-3 Year US Government/Corporate Index and Bloomberg Barclays U.S. Aggregate Bond Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled " More About Each Fund's Investments and Risks."

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

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N-1A

Amendment Flag

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false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

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Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Institutional Class Prospectus | Boston Partners Emerging Markets Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — BOSTON PARTNERS EMERGING MARKETS FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term growth of capital.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal period ended August 31, 2019, the portfolio turnover rate for the Fund was 155% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

155.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund will pursue its objective through a value oriented, research-driven strategy of investing in equity securities and financial instruments with equity like characteristics designed to provide exposure to emerging markets. Securities are selected by the Adviser using its "three circles" approach which combines a quantitative screening with a fundamental bottom up selection process. This investment strategy is grounded in the following principles: (1) low valuation stocks outperform high valuation stocks; (2) companies with strong fundamentals, e.g. high and sustainable returns on invested capital, outperform companies with weak fundamentals; and (3) stocks with positive business momentum, e.g. rising earnings estimates, outperform stocks with negative business momentum. The Adviser examines various factors in determining the value characteristics of issuers, including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals, such as return-on-equity and earnings growth and cash flow.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in the securities of emerging market issuers, related derivative instruments and other investments that are tied economically to emerging market countries. The Adviser considers an emerging market country to include any country that is: 1) generally recognized to be an emerging market country by the international financial community, including the World Bank; 2) classified by the United Nations as a developing country; or 3) included in the MSCI Emerging Markets Index. Due to the unique relationship between China and its separately administered regions, the Adviser includes Hong Kong and Macau as emerging markets, independent of above definitions 1 through 3. The Adviser determines that an investment is tied economically to an emerging market if such investment satisfies one or more of the following conditions: 1) the issuer’s primary trading market is in an emerging market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in emerging markets; 3) the investment is included in an index representative of emerging markets; and 4) the investment is exposed to the economic risks and returns of emerging markets.

In managing the Fund’s portfolio, the Adviser will seek to identify mispriced publicly traded equity securities of emerging market companies and purchase securities that the Adviser believes will outperform, emphasizing low valuation, positive business momentum and high quality.

The Fund’s portfolio is rebalanced regularly to maintain the optimal risk/return trade-off. The Adviser assesses each stock’s changing characteristics relative to its contribution to portfolio risk. The Adviser will sell a stock that the Adviser believes no longer offers an appropriate return-to-risk tradeoff. The Fund’s investment adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

The equity securities in which the Fund will invest, which may include equity securities of non-U.S. issuers that are traded in the markets of the United States, include equity securities issued by large-, mid- and small- or micro-cap companies, as well as exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers").

The Fund may invest up to 20% of its net assets in high yield debt obligations (commonly known as “junk bonds”), such as bonds and debentures, used by corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Junk bonds are rated BB or lower by S&P Global, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded. The Fund will primarily invest in fixed income instruments, including high yield debt obligations, when the Fund believes that such instruments offer a better risk/reward profile than comparable equity opportunities.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund’s investments will be spread over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest in exchange traded funds to the extent permitted by the Investment Company Act of 1940, as amended (“1940 Act”), and applicable SEC orders.

The Fund may participate as a purchaser in initial public offerings of securities (“IPOs”). An IPO is a company’s first offering of stock to the public.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may also seek to increase its income by lending portfolio securities.

The Fund will invest in derivatives, including put and call options, futures, contracts for differences, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes. Contracts for differences offer exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin. The Fund’s investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, contracts for differences, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Equity Securities Risk. The Fund may invest in, or have exposure to, equity securities. Equity securities tend to be more volatile than other investment choices, such as debt and money market instruments. The value of your investment may decrease in response to overall stock market movements or the value of individual securities.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in Junk Bonds, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such Junk Bonds are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium-capitalization stocks.

● Limited Operating History Risk: The Fund has a limited operating history upon which prospective investors can evaluate its performance. Although the investment strategies described herein may have been utilized by investment accounts managed by the Adviser’s investment team, past performance is not indicative of future results.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund makes may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

● Portfolio Turnover Risk. The Fund may frequently trade its portfolio securities, resulting in higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Segregated Account Risk. The Fund’s transactions in derivative instruments may require the Fund to establish a segregated account consisting of cash or liquid securities in an amount sufficient to cover the transactions. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund’s assets could impede portfolio management or the Fund’s ability to meet redemption requests or other current obligations.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the performance of the Boston Partners Emerging Markets Fund's Institutional Class. The bar chart below shows you the performance of the Fund’s Institutional Class for one year. This also provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart below shows you the performance of the Fund's Institutional Class for one year.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Year Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the period reflected in the chart above):

Best Quarter:	13.92% (quarter ended March 31, 2019)
Worst Quarter:	-11.07% (quarter ended December 31, 2018)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Market Index Changed

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Effective August 31, 2019, the Fund changed its primary index from the MSCI Emerging Markets Index - Gross Return to the MSCI Emerging Markets Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Institutional Class Prospectus | Boston Partners Emerging Markets Fund | MSCI Emerging Markets Index - Net Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

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18.42%

^[1]

Since Inception

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1.98%

^[1]

Inception Date

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Oct. 17, 2017

^[1]

Institutional Class Prospectus | Boston Partners Emerging Markets Fund | MSCI Emerging Markets Index - Gross Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

18.88%

^[1]

Since Inception

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2.37%

^[1]

Inception Date

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Oct. 17, 2017

^[1]

Institutional Class Prospectus | Boston Partners Emerging Markets Fund | Institutional Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

BPEMX

Management Fees

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0.85%

Distribution and/or Service (12b-1) Fees

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none

Other Expenses

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2.04%

Acquired fund fees and expenses

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0.04%

^[2]

Total Annual Fund Operating Expenses

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2.93%

Fee Waivers and/or Expense Reimbursements

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(1.83%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

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1.10%

One Year

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$ 1,121

Three Years

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7,337

Five Years

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13,812

Ten Years

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$ 31,210

Annual Return 2018

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(20.87%)

Annual Return 2019

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28.29%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Mar. 31, 2019

Highest Quarterly Return

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13.92%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Dec. 31, 2018

Lowest Quarterly Return

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(11.07%)

1 Year

rr_AverageAnnualReturnYear01

28.29%

Since Inception

rr_AverageAnnualReturnSinceInception

2.57%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 17, 2017

Institutional Class Prospectus | Boston Partners Emerging Markets Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

26.50%

^[4]

Since Inception

rr_AverageAnnualReturnSinceInception

1.84%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 17, 2017

^[4]

Institutional Class Prospectus | Boston Partners Emerging Markets Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

17.42%

Since Inception

rr_AverageAnnualReturnSinceInception

1.81%

Inception Date

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Oct. 17, 2017

[1] Effective August 31, 2019, the Fund changed its primary index from the MSCI Emerging Markets Index - Gross Return to the MSCI Emerging Markets Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.10% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

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Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Investor Class Prospectus | Boston Partners Small Cap Value Fund II

Prospectus [Line Items]

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Risk/Return [Heading]

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SUMMARY SECTION — BOSTON PARTNERS SMALL CAP VALUE FUND II

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Objective, Secondary [Text Block]

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Current income is a secondary objective.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

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February 28, 2021

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 29% of the average value of its portfolio.

Portfolio Turnover, Rate

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29.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

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Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers with small market capitalizations and identified by the Adviser as having value characteristics. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Value Index. The Russell 2000^® Value Index is an unmanaged index that contains stocks from the Russell 2000^® Index with less than average growth orientation. As of November 30, 2019, the median market capitalization of this index was $666 million and the largest stock was $6.7 billion. Please note that this range is as of a particular point in time and is subject to change.

The Fund generally invests in the equity securities of small companies. The Adviser will seek to invest in companies it considers to be well managed and to have attractive fundamental financial characteristics. The Adviser believes greater potential for price appreciation exists among small companies since they tend to be less widely followed by other securities analysts and thus may be more likely to be undervalued by the market. The Fund may invest from time to time a portion of its assets, not to exceed 20% (under normal conditions) at the time of purchase, in companies with larger market capitalizations.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may also invest up to 25% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Small Cap Companies Risk. The Fund will invest in smaller issuers which are more volatile and less liquid than investments in issuers with a market capitalization greater than the market capitalization of companies in the Russell 2000^® Value Index. Small market capitalization issuers are not as diversified in their business activities as issuers with market capitalizations greater than the market capitalization of companies in the Russell 2000^® Value Index and are more susceptible to changes in the business cycle.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the long-term performance of the Boston Partners Small Cap Value Fund II’s Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart below shows you how the performance of the Fund's Investor Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	14.79% (quarter ended December 31, 2010)
Worst Quarter:	-20.47% (quarter ended September 30, 2011)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund’s Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Investor Class Prospectus | Boston Partners Small Cap Value Fund II | Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

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22.39%

5 Years

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6.99%

10 Years

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10.56%

Investor Class Prospectus | Boston Partners Small Cap Value Fund II | Investor Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

BPSCX

Management Fees

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0.95%

^[1]

Distribution and/or Service (12b-1) Fees

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0.25%

Other Expenses

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0.21%

Acquired fund fees and expenses

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0.01%

^[2]

Total Annual Fund Operating Expenses

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1.42%

Fee Waivers and/or Expense Reimbursements

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(0.07%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

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1.35%

One Year

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$ 138

Three Years

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390

Five Years

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662

Ten Years

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$ 1,440

Annual Return 2010

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18.24%

Annual Return 2011

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(3.67%)

Annual Return 2012

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22.54%

Annual Return 2013

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34.40%

Annual Return 2014

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3.90%

Annual Return 2015

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(4.57%)

Annual Return 2016

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25.68%

Annual Return 2017

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9.50%

Annual Return 2018

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(16.56%)

Annual Return 2019

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27.71%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Dec. 31, 2010

Highest Quarterly Return

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14.79%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Sep. 30, 2011

Lowest Quarterly Return

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(20.47%)

1 Year

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27.71%

5 Years

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6.96%

10 Years

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10.56%

Investor Class Prospectus | Boston Partners Small Cap Value Fund II | Investor Class | After Taxes on Distributions

Prospectus [Line Items]

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1 Year

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27.01%

^[4]

5 Years

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5.89%

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10 Years

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9.94%

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Investor Class Prospectus | Boston Partners Small Cap Value Fund II | Investor Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

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1 Year

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16.86%

5 Years

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5.27%

10 Years

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8.64%

[1] Prior to October 1, 2019, the management fee was 1.00%.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.35% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.35%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time, the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.35% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Total

Investor Class Prospectus | Boston Partners Global Equity Fund

SUMMARY SECTION — BOSTON PARTNERS GLOBAL EQUITY FUND

Investment Objective

The Fund seeks to provide long-term capital growth.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Class Prospectus Boston Partners Global Equity Fund Investor Class
Management Fees	0.90%
Distribution and/or Service (12b-1) Fees	0.25%
Other Expenses	0.13%
Acquired fund fees and expenses	0.01%	[1]
Total Annual Fund Operating Expenses	1.29%
Fee Waivers and/or Expense Reimbursements	(0.09%)	[2]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	1.20%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Investor Class Prospectus | Boston Partners Global Equity Fund | Investor Class | USD ($)	122	348	591	1,288

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund’s Institutional Class was 97% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds (“ETFs”)) and real estate investment trusts (“REITs”), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by the Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Adviser applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Adviser considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer’s inherent value.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”).An IPO is a company’s first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds (“ETFs”) are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees in addition to the Fund’s own expenses.Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through “sponsored” or “unsponsored” facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes (“P-notes”) are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may “cover” a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage fund and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law, or (ii) maintain their exemptions from registrations under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. Redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

Performance Information

As of the date of this Prospectus, the Boston Partners Global Equity Fund’s Investor Class has not yet commenced operations. The bar chart and table below illustrate the performance of the Fund’s Institutional Class, which is offered in a separate Prospectus. Had the Investor Class been operational during the periods in the chart and table below, it would have had substantially similar annual returns as the Institutional Class because the Investor Class is invested in the same portfolio of securities. Annual returns would differ only to the extent that the Investor Class and Institutional Class do not have the same expenses. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risk of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	11.70% (quarter ended March 31, 2012)
Worst Quarter:	-14.86% (quarter ended December 31, 2018)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Average Annual Total Returns - Investor Class Prospectus - Boston Partners Global Equity Fund		1 Year	5 Years	Since Inception	Inception Date
Institutional Class		18.77%	6.31%	10.15%	Dec. 30, 2011
Institutional Class | After Taxes on Distributions	[1]	18.37%	5.60%	9.37%	Dec. 30, 2011
Institutional Class | After Taxes on Distributions and Sales		11.39%	4.85%	8.10%	Dec. 30, 2011
MSCI World Index - Net Return (reflects no deduction for fees, expenses or taxes)	[2]	27.67%	8.74%	11.21%	Dec. 30, 2011
MSCI World Index - Gross Return (reflects no deduction for fees, expenses or taxes)	[2]	28.40%	9.36%	11.85%	Dec. 30, 2011

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.20% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.20%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.20% or the expense cap then in effect, or whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

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Investor Class Prospectus | Boston Partners Long/Short Equity Fund

SUMMARY SECTION — BOSTON PARTNERS LONG/SHORT EQUITY FUND

Investment Objective

The Fund seeks long-term capital appreciation while reducing exposure to general equity market risk. The Fund seeks a total return greater than that of the S&P 500^® Index over a full market cycle.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Class Prospectus Boston Partners Long/Short Equity Fund Investor Class
Management Fees	2.25%
Distribution and/or Service (12b-1) Fees	0.25%
Other Expenses	0.21%
Dividend expense on short sales	0.22%
Interest expense on borrowings	none
Total Annual Fund Operating Expenses	2.93%
Fee Waivers and/or Expense Reimbursements	(0.50%)	[1]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	2.43%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Investor Class Prospectus | Boston Partners Long/Short Equity Fund | Investor Class | USD ($)	246	810	1,401	3,001

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 64% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage. The Fund invests, both long and short, in securities principally traded in the United States markets. The Fund may invest in securities of companies operating for three years or less (“unseasoned issuers”). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the United States equity market generally. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities.

Under normal circumstances, the Adviser expects that the Fund’s long positions will not exceed approximately 125% of the Fund’s net assets.

The Fund’s long and short positions may involve (without limit) equity securities of foreign issuers that are traded in the markets of the United States. The Fund may also invest up to 20% of its total assets directly in equity securities of foreign issuers.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations. High yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund’s assets could impede portfolio management or the Fund’s ability to meet redemption requests or other current obligations.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Equity Fund’s Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	13.42% (quarter ended December 31, 2010)
Worst Quarter:	-9.99% (quarter ended June 30, 2010)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods. Although the Fund compares its average total return to a broad-based securities market index, the Fund seeks returns that are not correlated to securities market returns. The Fund seeks to achieve a 12-15% return over a full market cycle; however, there can be no guarantee that such returns will be achieved.

Average Annual Total Returns - Investor Class Prospectus - Boston Partners Long/Short Equity Fund		1 Year	5 Years	10 Years
Investor Class		8.85%	2.54%	6.66%
Investor Class | After Taxes on Distributions	[1]	6.19%	1.13%	4.84%
Investor Class | After Taxes on Distributions and Sales		7.10%	1.89%	5.06%
S&P 500® Value Index (reflects no deduction for fees, expenses or taxes)		31.49%	11.70%	13.56%

[1] Effective February 28, 2020, the Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Investor Class shares exceeds 2.21% of the average daily net assets attributable to the Fund's Investor Class shares. Because dividend expenses on short sales, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 2.21%. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 2.21% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement. Prior to February 28, 2020, the Fund's Investor Class fee cap was 2.75%.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

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Matson Money | Free Market U.S. Equity Fund

FREE MARKET U.S. EQUITY FUND FMUEX

Investment Objective

The Free Market U.S. Equity Fund (for this section only, the “Fund”) seeks long-term capital appreciation.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Matson Money Free Market U.S. Equity Fund Institutional Class
Management Fees	0.49%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.06%
Acquired fund fees and expenses	0.30%	[1]
Total Annual Fund Operating Expenses	0.85%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Matson Money | Free Market U.S. Equity Fund | Institutional Class | USD ($)	87	272	473	1,053

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 7% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in equity securities, such as common stocks, preferred stocks or securities convertible into stocks, of U.S. companies, or invest substantially all of their assets in such equity securities. The Fund will diversify its investments by investing primarily in investment companies focusing on different segments of the equity markets, including large (“large-cap”), small (“small-cap”) and micro-capitalization (“micro-cap”) equity securities that the Fund’s investment adviser (“Adviser”) believes offer the prospect of long-term capital appreciation. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Fund’s net assets to be invested in the securities of investment companies that invest in the types of securities described in each asset class below, with less than 2% of the net assets invested in cash or money market instruments.

U.S. Large Cap Value Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of large cap companies that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time. Large cap companies are generally considered companies whose market capitalizations are generally in the highest 90% of total market capitalization or companies whose market capitalizations are larger than or equal to the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions.

U.S. Small Cap Value Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of small cap companies that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time. Small cap companies are generally considered companies whose market capitalizations are generally in the lowest 10% of total market capitalization or companies whose market capitalizations are smaller than the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions.

U.S. Large Company Asset Class: The underlying investment companies generally will purchase all of the stocks that comprise the S&P 500^® Index in approximately the proportions they are represented in the S&P 500^® Index. Generally, these are the U.S. stocks with the largest market capitalizations and, as a group, they represent approximately 80% of the total market capitalization of all publicly traded U.S. stocks.

U.S. Small Cap Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of small cap companies primarily based on market capitalization. Small cap companies are generally considered companies whose market capitalizations are generally in the lowest 10% of total market capitalization or companies whose market capitalizations are smaller than the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions. There may be some overlap in the companies in which the U.S. small cap asset class and the U.S. micro cap asset class invest.

U.S. Micro Cap Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of micro cap companies. Micro cap companies are generally considered companies whose market capitalizations are generally in the lowest 5% of total market capitalization or companies whose market capitalizations are smaller than the 1,500th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions. There may be some overlap in the companies in which the U.S. micro cap asset class and the U.S. small cap asset class invest.

The underlying investment companies may use derivatives, such as futures contracts and options on futures contracts for U.S. equity securities and indices, to adjust market exposure based on actual or expected cash inflows to or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, options and swaps to help the ETF track its underlying index.

The Fund reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Fund employs a temporary defensive measure, the Fund may not achieve its investment objective. Periodically the Adviser will review the allocations for the Fund in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Fund in the underlying investment companies without notice to shareholders.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Stocks of large cap, small cap or micro cap companies in which the Fund’s underlying investment companies invest or in which the Fund invests directly may temporarily fall out of favor with investors or may be more volatile than the rest of the U.S. market as a whole.

● The smaller the capitalization of a company, generally the less liquid its stock and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records and are more likely to fail than companies with larger market capitalizations.

● Although the Fund will invest in other investment companies that follow a value oriented strategy, value stocks may perform differently from the market as a whole and such a strategy may cause the Fund at times to underperform equity funds that use other investment strategies.

● Companies in which the Fund’s underlying investment companies invest may suffer unexpected losses or lower than expected earnings or their securities may become difficult or impossible to sell at the time and for the price that the underlying investment adviser(s) would like.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Fund could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Fund invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in U.S. equity securities, the NAV of the Fund will change with changes in the share prices of the investment companies in which the Fund invests.

● There is a risk that large, small or micro capitalization stocks may not perform as well as other asset classes or the U.S. stock market as a whole. In the past, large, small and micro capitalization stocks have gone through cycles of doing better or worse than the stock market in general.

● There is a risk that the Fund, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Fund will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

More information about the Fund’s investments and risks is contained under the section entitled “More About Each Fund’s Investments and Risks.”

Performance Information

The chart below illustrates the long-term performance of the Fund. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 15.21% (quarter ended December 31, 2010)

Worst Quarter: -21.03% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns of the Fund before and after taxes for the past calendar year, the past five calendar years, and past ten calendar years to the average total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Matson Money - Free Market U.S. Equity Fund		1 Year	5 Years	10 Years
Institutional Class		22.47%	7.28%	11.62%
Institutional Class | After Taxes on Distributions	[1]	20.93%	5.87%	10.63%
Institutional Class | After Taxes on Distributions and Sales		14.40%	5.49%	9.51%
Russell 2500® Index (reflects no deduction for fees, expenses or taxes)		27.77%	8.93%	12.58%
Composite Index	[2]	26.63%	8.85%	11.96%

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] The Composite Index is comprised of the S&P 500® Index, Russell 1000® Value Index, Russell 2000® Index and Russell 2000® Value Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Fund's Investments and Risks."

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Prospectus [Line Items]

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485BPOS

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RBB FUND, INC.

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Feb. 28, 2020

Institutional Class Prospectus | Boston Partners Long/Short Research Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — BOSTON PARTNERS LONG/SHORT RESEARCH FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term total return.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 60% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

60.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund uses a hedged strategy. The Fund actively invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales (i.e. sales of securities the Fund does not own) are invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage.

The Fund invests, both long and short, in equity securities issued by large-, mid- and small (or “micro”) cap companies, as well as other instruments that are convertible into equity securities. Selling securities short is a form of leverage. Equity securities in which the Fund may invest include exchange-traded and over-the-counter common and preferred stocks, warrants, rights, convertible securities, depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies and real estate investment trusts (“REITs”), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less (“unseasoned issuers”). The Fund may also invest in depositary receipts and equity securities of foreign companies (denominated in either U.S. dollars or foreign currencies), put and call options, futures, indexed securities and fixed-income securities (including bonds, notes, asset-backed securities, convertible securities, Eurodollar and Yankee dollar instruments, preferred stocks and money market instruments) and high yield securities (commonly referred to as “junk bonds”). Fixed income securities in which the Fund invests include those rated between AAA and D by a nationally recognized statistical rating organization, or deemed of comparable quality by the Adviser. The Adviser may also temporarily invest uninvested cash in money market funds and similar collective investment vehicles. The Fund may also seek to increase its income by lending portfolio securities.

The Adviser determines the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the U.S. equity market by investing less than 100% of its assets in net long positions. Selection of individual securities to be held long or sold short will be based on a mix of quantitative techniques and fundamental security analysis. The Adviser selects stocks on the basis of three criteria: value, fundamental business strength and momentum. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

Although the Fund seeks to follow a hedged strategy, there can be no assurance that the Fund’s portfolio or investments will be insulated from market moves or effectively hedged against risk.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest in exchange traded funds to the extent permitted by the Investment Company Act of 1940, as amended (“1940 Act”), and applicable SEC orders.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The principal derivative instruments in which the Fund invests are futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps. The Fund’s investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Exchange-Traded Fund Risk. Exchange-traded funds (“ETFs”) are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations (of any rating, including defaulted securities and unrated securities), including bonds and debentures, issued by corporations and business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● Indexed Securities Risk. The Fund may invest in indexed securities whose value is linked to securities indices. Most such securities have values that rise and fall according to the change in one or more specified indices and may have characteristics similar to direct investments in the underlying securities. Depending on the index, such securities may have greater volatility than the market as a whole.

● Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may be incorrect in the stocks it buys and believes to be undervalued and in stocks it sells short and believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 300%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund’s obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales “against the box” may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not “against the box” involve a form of investment leverage, and the amount of the Fund’s loss on a short sale is potentially unlimited.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Research Fund’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	8.37% (quarter ended December 31, 2011)
Worst Quarter:	-9.89% (quarter ended September 30, 2011)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of a broad-based securities market index for the same periods.

Institutional Class Prospectus | Boston Partners Long/Short Research Fund | S&P 500® Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

31.49%

5 Years

rr_AverageAnnualReturnYear05

11.70%

Since Inception

rr_AverageAnnualReturnSinceInception

14.26%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2010

Institutional Class Prospectus | Boston Partners Long/Short Research Fund | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

BPIRX

Management Fees

rr_ManagementFeesOverAssets

1.25%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.13%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.15%

^[1]

One Year

rr_ExpenseExampleYear01

$ 2,181

Three Years

rr_ExpenseExampleYear03

6,730

Five Years

rr_ExpenseExampleYear05

11,543

Ten Years

rr_ExpenseExampleYear10

$ 24,827

Annual Return 2011

rr_AnnualReturn2011

3.40%

Annual Return 2012

rr_AnnualReturn2012

13.37%

Annual Return 2013

rr_AnnualReturn2013

17.77%

Annual Return 2014

rr_AnnualReturn2014

7.15%

Annual Return 2015

rr_AnnualReturn2015

1.52%

Annual Return 2016

rr_AnnualReturn2016

3.62%

Annual Return 2017

rr_AnnualReturn2017

10.10%

Annual Return 2018

rr_AnnualReturn2018

(10.59%)

Annual Return 2019

rr_AnnualReturn2019

12.58%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

8.37%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.89%)

1 Year

rr_AverageAnnualReturnYear01

12.58%

5 Years

rr_AverageAnnualReturnYear05

3.11%

Since Inception

rr_AverageAnnualReturnSinceInception

6.83%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2010

Institutional Class Prospectus | Boston Partners Long/Short Research Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

11.97%

^[2]

5 Years

rr_AverageAnnualReturnYear05

2.57%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

6.45%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2010

^[2]

Institutional Class Prospectus | Boston Partners Long/Short Research Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

7.87%

5 Years

rr_AverageAnnualReturnYear05

2.37%

Since Inception

rr_AverageAnnualReturnSinceInception

5.48%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2010

[1] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to forgo all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) exceeds 1.50% of the average daily net assets attributable to the Fund's Institutional Class shares. Because short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 1.50%. This contractual limitation is in effect until at least February 28, 2021 and may not be terminated without Board approval. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.50% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Feb. 28, 2020

Document Effective Date

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Feb. 28, 2020

Prospectus Date

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Feb. 28, 2020

Institutional Class Prospectus | Boston Partners Global Equity Fund

Prospectus [Line Items]

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Risk/Return [Heading]

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SUMMARY SECTION — BOSTON PARTNERS GLOBAL EQUITY FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The Fund seeks to provide long-term capital growth.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

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February 28, 2021

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 97% of the average value of its portfolio.

Portfolio Turnover, Rate

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97.00%

Expense Exchange Traded Fund Commissions [Text]

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You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

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Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity- related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by the Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Adviser applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Adviser considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer's inherent value.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

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The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the long-term performance of the Boston Partners Global Equity Fund's Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	11.70% (quarter ended March 31, 2012)
Worst Quarter:	-14.86% (quarter ended December 31, 2018)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Market Index Changed

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Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Institutional Class Prospectus | Boston Partners Global Equity Fund | MSCI World Index - Net Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

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27.67%

^[1]

5 Years

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8.74%

^[1]

Since Inception

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11.21%

^[1]

Inception Date

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Dec. 30, 2011

^[1]

Institutional Class Prospectus | Boston Partners Global Equity Fund | MSCI World Index - Gross Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

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28.40%

^[1]

5 Years

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9.36%

^[1]

Since Inception

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11.85%

^[1]

Inception Date

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Dec. 30, 2011

^[1]

Institutional Class Prospectus | Boston Partners Global Equity Fund | Institutional Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

BPGIX

Management Fees

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0.90%

Distribution and/or Service (12b-1) Fees

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none

Other Expenses

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0.13%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[2]

Total Annual Fund Operating Expenses

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1.04%

Fee Waivers and/or Expense Reimbursements

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(0.09%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

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0.95%

One Year

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$ 969

Three Years

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3,220

Five Years

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5,653

Ten Years

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$ 12,629

Annual Return 2012

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15.34%

Annual Return 2013

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32.67%

Annual Return 2014

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4.34%

Annual Return 2015

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0.80%

Annual Return 2016

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8.50%

Annual Return 2017

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20.37%

Annual Return 2018

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(13.15%)

Annual Return 2019

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18.77%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Mar. 31, 2012

Highest Quarterly Return

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11.70%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Dec. 31, 2018

Lowest Quarterly Return

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(14.86%)

1 Year

rr_AverageAnnualReturnYear01

18.77%

5 Years

rr_AverageAnnualReturnYear05

6.31%

Since Inception

rr_AverageAnnualReturnSinceInception

10.15%

Inception Date

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Dec. 30, 2011

Institutional Class Prospectus | Boston Partners Global Equity Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

18.37%

^[4]

5 Years

rr_AverageAnnualReturnYear05

5.60%

^[4]

Since Inception

rr_AverageAnnualReturnSinceInception

9.37%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

^[4]

Institutional Class Prospectus | Boston Partners Global Equity Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

11.39%

5 Years

rr_AverageAnnualReturnYear05

4.85%

Since Inception

rr_AverageAnnualReturnSinceInception

8.10%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

[1] Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 0.95% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.95%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 0.95% or the expense cap then in effect, or whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Abbey Capital | Abbey Capital Futures Strategy Fund

Prospectus [Line Items]

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Risk/Return [Heading]

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SUMMARY SECTION

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The investment objective of the Abbey Capital Futures Strategy Fund (the “Fund”) is to seek long-term capital appreciation.

Objective, Secondary [Text Block]

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Current income is a secondary objective.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund (the “Shares”). You may qualify for sales charge discounts if you invest, or agree to invest in the future, at least $25,000 in Class A Shares or at least $250,000 in Class T Shares of the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information – Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information – Reducing or Eliminating the Front-End Sales Charge.” Financial intermediaries may impose different sales charge waivers for Class A Shares and Class T Shares, and these variations are described in Appendix A of the Prospectus. Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 0% of the average value of its portfolio. In accordance with industry practice, derivative instruments and instruments with a maturity of one year or less at the time of acquisition are excluded from the calculation of the portfolio turnover rate, which leads to the 0% portfolio turnover rate reported above. If those instruments were included in the calculation, the Fund would have a high portfolio turnover rate.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

none

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you invest, or agree to invest in the future, at least $25,000 in Class A Shares or at least $250,000 in Class T Shares of the Fund.

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Other Expenses, New Fund, Based on Estimates [Text]

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"Other Expenses" for Class T Shares, which had not commenced operations as of the date of this Prospectus, are estimated for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in Class A, Class C and Class T Shares, and $1,000,000 in Class I Shares, in the Fund for the time periods indicated and then redeem all of your Shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same (taking into account the contractual expense limitation until its expiration). Although your actual costs may be higher or lower, based on these assumptions your costs of investing in the Fund would be:

Expense Example, No Redemption Narrative [Text Block]

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You would pay the following expenses on Class C Shares if you did not redeem your shares at the end of the period:

Strategy [Heading]

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Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund seeks to achieve its investment objective by allocating its assets between a “Managed Futures” strategy and a “Fixed Income” strategy.

The Managed Futures strategy will be achieved by the Fund investing a portion of its assets in Abbey Capital Onshore Series LLC, a wholly-owned and controlled Delaware series limited liability company (the “Onshore Subsidiary”) and up to 25% of its total assets in Abbey Capital Master Offshore Fund Limited, a wholly-owned and controlled subsidiary of the Fund organized under the laws of the Cayman Islands (the “Cayman Subsidiary”). The Cayman Subsidiary will in turn invest all or substantially all of its assets in segregated portfolios of Abbey Capital Offshore Fund SPC (the “SPC” and, together with the Onshore Subsidiary and the Cayman Subsidiary, the “Subsidiaries”), a wholly-owned and controlled segregated portfolio company incorporated under the laws of the Cayman Islands. The Cayman Subsidiary will serve solely as an intermediate entity through which the Fund will invest in the SPC. The Cayman Subsidiary makes no independent investment decisions and has no investment or other discretion over the Fund’s investable assets. The Adviser may allocate assets of the SPC and the Onshore Subsidiary to multiple Managed Futures portfolios (the “Segregated Portfolios”) that include investment styles or sub-strategies such as (i) trend following, (ii) discretionary, fundamentals-based investing with a focus on macroeconomic analysis, (iii) strategies that pursue both fundamental and technical trading approaches, (iv) other specialized approaches to specific or individual market sectors such as equities, interest rates, metals, agricultural and soft commodities, and (v) systematic trading strategies which incorporate technical and fundamental variables.

The Managed Futures strategy investments are designed to achieve capital appreciation in the financial and commodities futures markets. The Adviser intends to allocate the assets of the SPC and the Onshore Subsidiary to one or more Trading Advisers to manage in percentages determined at the discretion of the Adviser. Each Trading Adviser will manage one or more of its own Segregated Portfolios. Each Trading Adviser invests according to a Managed Futures strategy in one or a combination of (i) options, (ii) futures, (iii) forwards, (iv) spot contracts, or (v) swaps, including total return swaps, each of which may be tied to (i) commodities, (ii) financial indices and instruments, (iii) foreign currencies, or (iv) equity indices. All commodities futures and commodities-related investments will be made in the Segregated Portfolios of the SPC. Each current Trading Adviser is registered with the U.S. Commodity Futures Trading Commission (the “CFTC”) as a Commodity Trading Advisor. Trading Advisers that are not registered with the SEC as investment advisers provide advice only regarding matters that do not involve securities.

The Fixed Income strategy invests the Fund’s assets primarily in investment grade fixed income securities (of all durations and maturities) in order to generate interest income and capital appreciation, which may add diversification to the returns generated by the Fund’s Managed Futures strategy. The Fund must set aside liquid assets, or engage in other SEC or staff-approved measures, to “cover” open positions with respect to certain kinds of derivative instruments. The Fixed Income strategy investments may be used to help cover the Fund’s derivative positions.

The Fund’s Adviser seeks returns, in part, by (i) using Managed Futures strategy investments that are not expected to have returns that are highly correlated to the broad equity market, and (ii) through actively managed Fixed Income strategy investments that are not expected to have returns that are highly correlated to the broad equity market or the Managed Futures strategy. The Adviser believes that utilizing non-correlated strategies may mitigate losses in generally declining markets. However, there can be no assurance that losses will be avoided. Investment strategies that have historically been non-correlated or demonstrated low correlations to one another or to major world financial market indices may become correlated at certain times, such as during a liquidity crisis in global financial markets.

The trading strategies employ several different trading styles using different research and trading methodologies, in a wide range of global financial and commodity markets operating over multiple time frames. Many of the styles use systematic, automated trading systems, using a combination of mathematical, statistical, technical analysis, pattern recognition and macroeconomic models aimed at profiting from market trends of different durations. Trading Advisers may use discretionary approaches aimed at identifying value investments and turning points in trends. All Trading Advisers utilize a disciplined approach to risk management. The Adviser and Trading Advisers from time to time will employ hedging techniques. Key principles of the Fund’s sell discipline include predetermined relative-value objectives for sectors, issuers and specific securities, pricing performance or fundamental performance that varies from expectations, deteriorating fundamentals, overvaluation and alternative investments offering the opportunity to achieve more favorable risk-adjusted returns.

The markets traded include bonds, money markets, foreign exchange markets and commodity markets. Most of the trading is done in derivative markets, usually listed futures markets, but some trading in cash markets may take place when this is the most effective way to enter or exit a trading position. Both long and short positions will be taken in all markets traded. Contracts are positioned either long or short based on various characteristics related to their prices. For example, the Fund may short a particular underlying security or instrument if the Adviser or a Trading Adviser believes the price of the underlying security or instrument will decrease. The Fund invests in U.S. and non-U.S. markets and in developed and emerging markets.

As much of the trading within the Fund is in futures markets, the Fund is likely to have cash balances surplus to margin requirements. The cash portfolio will be invested on a short-term, highly liquid, basis, to meet margin calls on the futures positions.

The Fund is “non-diversified” for purposes of the Investment Company Act of 1940, as amended, (the “1940 Act”) which means that the Fund may invest in fewer securities at any one time than a diversified fund. The Fund may not invest more than 15% of its net assets in illiquid securities. The Fund’s investments in certain derivative instruments and its short selling activities involve the use of leverage.

Generally, the SPC invests primarily in commodity futures but it may also invest in financial futures, options, forwards, spot contracts and swap contracts, fixed income securities, pooled investment vehicles, including those that are not registered pursuant to the 1940 Act and other investments intended to serve as margin or collateral for the SPC’s derivative positions. The Onshore Subsidiary only invests in financial futures, options, forwards, spot contracts and swap contracts, fixed income securities, pooled investment vehicles, including those that are not registered pursuant to the 1940 Act, and other investments intended to serve as margin or collateral for derivative positions. The Fund invests in the SPC in order to gain exposure to the commodities markets within the limitations of the federal tax laws, rules and regulations that apply to registered investment companies. Unlike the Fund and Onshore Subsidiary, the SPC may invest without limitation in commodity-linked derivatives, however, the SPC complies with the same 1940 Act asset coverage requirements with respect to its investments in commodity-linked derivatives that are applicable to the Fund’s transactions in derivatives. The Fund complies with Section 8 and Section 18 of the 1940 Act, governing investment policies and capital structure and leverage, respectively, on an aggregate basis with the Subsidiaries. The Subsidiaries also comply with Section 17 of the 1940 Act relating to affiliated transactions and custody.

In addition, to the extent applicable to the investment activities of the Subsidiaries, the Subsidiaries are subject to the same fundamental investment restrictions and will follow the same compliance policies and procedures as the Fund. Unlike the Fund, none of the Subsidiaries will seek to qualify as a regulated investment company (“RIC”) under Subchapter M of Subtitle A, Chapter 1, of the Internal Revenue Code of 1986, as amended (the “Code”). The Fund is, directly or indirectly, the sole shareholder of each Subsidiary and does not expect shares of the Subsidiaries to be offered or sold to other investors.

Risk [Heading]

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Principal Investment Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

The principal risk factors affecting shareholders’ investments in the Fund (and, indirectly, in the Subsidiaries) are set forth below.

● Commodity Sector Risk: Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative instruments may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments. The prices of energy, industrial metals, precious metals, agriculture and livestock sector commodities may fluctuate widely due to factors such as changes in value, supply and demand and governmental regulatory policies. The commodity-linked securities in which the Fund invests may be issued by companies in the financial services sector, and events affecting the financial services sector may cause the Fund’s Share value to fluctuate.

● Counterparty Risk: Counterparty risk is the risk that the other party(s) to an agreement or a participant to a transaction, such as a broker or the futures commission merchant, might default on a contract or fail to perform by failing to pay amounts due or failing to fulfill the obligations of the contract or transaction.

● Credit Risk: Credit risk refers to the possibility that the issuer of the security will not be able to make principal and interest payments when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. Securities rated in the four highest categories by the rating agencies are considered investment grade but they may also have some speculative characteristics. Investment grade ratings do not guarantee that bonds will not lose value.

● Currency Risk: Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls. Forward foreign currency exchange contracts may limit potential gains from a favorable change in value between the U.S. dollar and foreign currencies. Unanticipated changes in currency pricing may result in poorer overall performance for the Fund than if it had not engaged in these contracts.

● Cyber Security Risk: Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk: The Fund’s investments in derivative instruments including options, forward currency exchange contracts, swaps and futures, which may be leveraged, may result in losses. Investments in derivative instruments may result in losses exceeding the amounts invested.

● Emerging Markets Risk: Investment in emerging market securities involves greater risk than that associated with investment in foreign securities of developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Fixed Income Securities Risk: Fixed income securities in which the Fund may invest are subject to certain risks, including: interest rate risk, prepayment risk and credit/default risk. Interest rate risk involves the risk that prices of fixed income securities will rise and fall in response to interest rate changes. Prepayment risk involves the risk that in declining interest rate environments prepayments of principal could increase and require the Fund to reinvest proceeds of the prepayments at lower interest rates. Credit risk involves the risk that the credit rating of a security may be lowered.

● Foreign Investments Risk: International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through “sponsored” or “unsponsored” facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders.

● Forward and Futures Risk: The successful use of forward and futures contracts draws upon the Adviser’s and Trading Advisers’ skill and experience with respect to such instruments and are subject to special risk considerations. The primary risks associated with the use of futures contracts are (a) the imperfect correlation between the change in market value of instruments held by the Fund and the price of the forward or futures contract; (b) possible lack of a liquid secondary market, and possible regulatory position limits and restrictions, for a forward or futures contract and the resulting inability to close a forward or futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s and Trading Advisers’ inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; (e) the possibility that the counterparty will default in the performance of its obligations; and (f) if the Fund has insufficient cash, it may have to sell securities from its portfolio to meet daily variation margin requirements, and the Fund may have to sell securities at a time when it may be disadvantageous to do so.

● Hedging Transactions Risk: The Adviser and Trading Advisers from time to time employ various hedging techniques. The success of the Fund’s hedging strategy will be subject to the Adviser’s and Trading Advisers’ ability to correctly assess the degree of correlation between the performance of the instruments used in the hedging strategy and the performance of the investments in the portfolio being hedged. Since the characteristics of many securities change as markets change or time passes, the success of the Fund’s hedging strategy will also be subject to the Adviser’s and Trading Advisers’ ability to continually recalculate, readjust, and execute hedges in an efficient and timely manner. For a variety of reasons, the Adviser and Trading Advisers may not seek to establish a perfect correlation between such hedging instruments and the portfolio holdings being hedged. Such imperfect correlation may prevent the Fund from achieving the intended hedge or expose the Fund to risk of loss. In addition, it is not possible to hedge fully or perfectly against any risk, and hedging entails its own cost.

● High Portfolio Turnover Risk: The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions, and cause higher levels of current tax liability to shareholders in the Fund.

● Interest Rate Risk: Interest rate risk is the risk that prices of fixed income securities generally increase when interest rates decline and decrease when interest rates increase. The Fund may lose money if short term or long term interest rates rise sharply or otherwise change in a manner not anticipated by the Adviser and Trading Advisers. It is likely there will be less governmental action in the near future to maintain low interest rates. The negative impact on fixed income securities from the resulting rate increases for that and other reasons could be swift and significant.

● Leveraging Risk: Investments in derivative instruments may give rise to a form of leverage. Trading Advisers may engage in speculative transactions which involve substantial risk and leverage, such as making short sales. The use of leverage by the Adviser and Trading Advisers may increase the volatility of the Fund. These leveraged instruments may result in losses to the Fund or may adversely affect the Fund’s net asset value (“NAV”) or total return, because instruments that contain leverage are more sensitive to changes in interest rates. The Fund may also have to sell assets at inopportune times to satisfy its obligations in connection with such transactions.

● Management Risk: The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Manager Risk: If the Adviser and Trading Advisers make poor investment decisions, it will negatively affect the Fund’s investment performance.

● Market Risk: The NAV of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money.

● Multi-Manager Dependence Risk: The success of the Fund’s investment strategy depends both on the Adviser’s ability to select Trading Advisers and to allocate assets to those Trading Advisers and on each Trading Adviser’s ability to execute the relevant strategy and select investments for the Fund and the Subsidiaries. The Trading Advisers’ investment styles may not always be complementary, which could adversely affect the performance of the Fund.

● New Adviser Risk: The Trading Advisers may be newly registered or not registered with the SEC and/or have not previously managed a mutual fund. Accordingly, investors in the Fund bear the risk that a Trading Adviser’s inexperience may limit its effectiveness.

● Non-Diversification Risk: The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk: Purchasing and writing put and call options are highly specialized activities and entail greater than ordinary investment risks. The Fund may not fully benefit from or may lose money on an option if changes in its value do not correspond as anticipated to changes in the value of the underlying securities.

● Quantitative Trading Strategies Risk: The Adviser and Trading Advisers may use quantitative methods to select investments. Securities or other investments selected using quantitative methods may perform differently from the market as a whole or from their expected performance for many reasons, including factors used in building the quantitative analytical framework, the weights placed on each factor, and changing sources of market returns, among others. Any errors or imperfections in quantitative analyses or models, or in the data on which they are based, could adversely affect the ability of the Adviser or a Trading Adviser to use such analyses or models effectively, which in turn could adversely affect the Fund’s performance. There can be no assurance that these methodologies will help the Fund to achieve its investment objective.

● Short Sales Risk: Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund’s obligations to provide collateral to the lender and set aside assets to cover the open position. The Fund may engage in short sales that are either “uncovered” or “against the box.” A short sale is “against the box” if at all times during which the short position is open, the Fund owns at least an equal amount of the securities or securities convertible into, or exchangeable without further consideration for, securities of the same issue as the securities that are sold short. Short sales “against the box” may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not “against the box” involve a form of investment leverage, and the amount of the Fund’s loss on a short sale is potentially unlimited.

● Subsidiary Risk: By investing in the Subsidiaries, the Fund is indirectly exposed to the risks associated with each Subsidiary’s investments. The derivatives and other investments held by the Subsidiaries are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund. The Subsidiaries are not registered under the 1940 Act, and, unless otherwise noted in this Prospectus, are not subject to all the investor protections of the 1940 Act. Changes in the laws of the United States, Delaware and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiaries to continue to operate as they currently do and could adversely affect the Fund.

● Tax Risk: In order to qualify as a RIC, the Fund must meet certain requirements regarding the source of its income, the diversification of its assets and the distribution of its income. Under the test regarding the source of a RIC’s income, at least 90% of the gross income of the RIC each year must be qualifying income, which consists of dividends, interest, gains on investment assets and other categories of investment income. In 2006, the Internal Revenue Service (“IRS”) published a ruling that income realized from swaps with respect to a commodities index would not be qualifying income. The Fund’s investment in the SPC (via the Cayman Subsidiary) is expected to provide the Fund with exposure to the commodities markets within the limitations of the Code for qualification as a RIC, but there is a risk that the IRS could assert that the income derived from the investment in the SPC and certain commodity-linked structured notes will not be considered qualifying income for purposes of the Fund remaining qualified as a RIC for U.S. federal income tax purposes. If the Fund were to fail to qualify as a RIC and became subject to federal income tax, shareholders of the Fund would be subject to diminished returns. Changes in the laws of the United States, Delaware and/or the Cayman Islands could result in the inability of the Fund and/or its Subsidiaries to operate as described in this Prospectus and the SAI and could adversely affect the Fund. For example, the Cayman Islands does not currently impose any income, corporate or capital gains tax or withholding tax on the Cayman Subsidiary or the SPC. If Cayman Islands law changes such that the Cayman Subsidiary and/or the SPC must pay Cayman Islands taxes, Fund shareholders would likely suffer decreased investment returns.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

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The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The following performance information provides some indication of the risks of investing in the Fund. The bar chart shows the performance of the Fund’s Class I Shares from year to year. Performance information represents only past performance, before and after taxes, and does not necessarily indicate future results. Updated performance information is available online at www.abbeycapital.com or by calling 1-844-261-6484 (toll free).

Performance Information Illustrates Variability of Returns [Text]

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The following performance information provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-844-261-6484

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.abbeycapital.com

Performance Past Does Not Indicate Future [Text]

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Performance information represents only past performance, before and after taxes, and does not necessarily indicate future results.

Bar Chart [Heading]

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Abbey Capital Futures Strategy Fund – Class I Shares Total Returns for Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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During the period shown in the chart, the highest quarterly return was 8.86% (for the quarter ended March 31, 2015) and the lowest quarterly return was -4.90% (for the quarter ended June 30, 2015).

Performance Table Heading

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AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

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After-tax returns are shown for Class I Shares only.

Performance Table Explanation after Tax Higher

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In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

Performance Table Narrative

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The following table, which includes all applicable sales loads, compares the average annual total returns of the Class I Shares, Class A Shares and Class C Shares for the one-year, five-year, and since inception periods to a broad-based market index for the same periods. Average annual returns for Class T Shares are not included because they had not commenced operations prior to the date of this Prospectus. The returns for Class T Shares would be substantially similar to returns for Class I Shares because the shares are invested in the same portfolio of securities, and would differ only to the extent that the classes have different expenses.

Abbey Capital | Abbey Capital Futures Strategy Fund | S&P 500® Total Return Index (reflects no deduction for fees, expenses and taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

31.49%

5 Years

rr_AverageAnnualReturnYear05

11.70%

Since Inception

rr_AverageAnnualReturnSinceInception

11.64%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 01, 2014

Abbey Capital | Abbey Capital Futures Strategy Fund | Class I Shares

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

ABYIX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

1.77%

^[1]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.12%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.89%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.79%

^[2]

One Year

rr_ExpenseExampleYear01

$ 18,187

Three Years

rr_ExpenseExampleYear03

58,423

Five Years

rr_ExpenseExampleYear05

101,201

Ten Years

rr_ExpenseExampleYear10

$ 220,344

Annual Return 2015

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4.12%

Annual Return 2016

rr_AnnualReturn2016

(3.81%)

Annual Return 2017

rr_AnnualReturn2017

(0.09%)

Annual Return 2018

rr_AnnualReturn2018

(6.15%)

Annual Return 2019

rr_AnnualReturn2019

8.85%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

highest quarterly return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2015

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

8.86%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

lowest quarterly return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(4.90%)

1 Year

rr_AverageAnnualReturnYear01

8.85%

5 Years

rr_AverageAnnualReturnYear05

0.44%

Since Inception

rr_AverageAnnualReturnSinceInception

3.57%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 01, 2014

Abbey Capital | Abbey Capital Futures Strategy Fund | Class I Shares | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

5.51%

^[3]

5 Years

rr_AverageAnnualReturnYear05

(0.22%)

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

2.79%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 01, 2014

^[3]

Abbey Capital | Abbey Capital Futures Strategy Fund | Class I Shares | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

5.46%

^[3]

5 Years

rr_AverageAnnualReturnYear05

0.09%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

2.45%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 01, 2014

^[3]

Abbey Capital | Abbey Capital Futures Strategy Fund | Class A Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

ABYAX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.75%

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[4]

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

1.77%

^[1]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.12%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.14%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.04%

^[2]

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 25,000

One Year

rr_ExpenseExampleYear01

770

Three Years

rr_ExpenseExampleYear03

1,197

Five Years

rr_ExpenseExampleYear05

1,649

Ten Years

rr_ExpenseExampleYear10

$ 2,898

1 Year

rr_AverageAnnualReturnYear01

2.40%

5 Years

rr_AverageAnnualReturnYear05

(0.99%)

Since Inception

rr_AverageAnnualReturnSinceInception

2.21%

^[5]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 01, 2014

Abbey Capital | Abbey Capital Futures Strategy Fund | Class C Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

ABYCX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[6]

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

1.77%

^[1]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses

rr_OtherExpensesOverAssets

0.12%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.89%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.79%

^[2]

One Year

rr_ExpenseExampleYear01

$ 382

Three Years

rr_ExpenseExampleYear03

885

Five Years

rr_ExpenseExampleYear05

1,514

Ten Years

rr_ExpenseExampleYear10

3,207

One Year

rr_ExpenseExampleNoRedemptionYear01

282

Three Years

rr_ExpenseExampleNoRedemptionYear03

885

Five Years

rr_ExpenseExampleNoRedemptionYear05

1,514

Ten Years

rr_ExpenseExampleNoRedemptionYear10

$ 3,207

1 Year

rr_AverageAnnualReturnYear01

7.75%

5 Years

rr_AverageAnnualReturnYear05

(0.55%)

Since Inception

rr_AverageAnnualReturnSinceInception

2.55%

^[5]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 01, 2014

Abbey Capital | Abbey Capital Futures Strategy Fund | Class T Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

2.50%

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

1.77%

^[1]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.12%

^[7]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.14%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.10%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.04%

^[2]

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 250,000

One Year

rr_ExpenseExampleYear01

452

Three Years

rr_ExpenseExampleYear03

894

Five Years

rr_ExpenseExampleYear05

1,362

Ten Years

rr_ExpenseExampleYear10

$ 2,653

[1] Management Fees include advisory fees paid to both Abbey Capital Limited (the "Adviser") and one or more trading advisers (the "Trading Advisers"). There are no performance fees charged by the Adviser or Trading Advisers either at the Fund or at the Fund's wholly-owned Subsidiaries.

[2] The Adviser has contractually agreed to waive its advisory fee and/or reimburse expenses in order to limit Total Annual Fund Operating Expenses (excluding certain items discussed below) to 1.79%, 2.04%, 2.79% and 2.04% of the Fund's average daily net assets attributable to Class I Shares, Class A Shares, Class C Shares and Class T Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total Annual Fund Operating Expenses to exceed 1.79%, 2.04%, 2.79% or 2.04%, as applicable: acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 for Class I Shares, Class A Shares, Class C Shares and Class T Shares, and may not be terminated prior to that date without the approval of the Board of Directors of The RBB Fund, Inc. (the "Company"). If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.79%, 2.04%, 2.79% and 2.04%, as applicable, the Adviser may recoup any waived or reimbursed amounts from the Fund within three years from the date on which such waiver or reimbursement was made by the Adviser, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[3] After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class I Shares only. After-tax returns for Class A Shares, Class C Shares and Class T Shares will vary.

[4] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Class A Shares made within 12 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[5] Class I Shares commenced operations on July 1, 2014, Class A Shares commenced operations on August 29, 2014, and Class C Shares commenced operations on October 6, 2015. Performance shown prior to inception of the Class A Shares and Class C Shares is based on the performance of Class I Shares, adjusted for the higher expenses applicable to Class A Shares and Class C Shares, respectively.

[6] The CDSC applies to redemptions of Class C Shares made within 12 months of purchase and will be assessed on an amount equal to the lesser of the offering price at the time of purchase of the shares redeemed and the net asset value of the shares redeemed at the time of redemption.

[7] "Other Expenses" for Class T Shares, which had not commenced operations as of the date of this Prospectus, are estimated for the current fiscal year.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Institutional Class Prospectus | Boston Partners Small Cap Value Fund II

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — BOSTON PARTNERS SMALL CAP VALUE FUND II

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

Current income is a secondary objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 29% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

29.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers with small market capitalizations and identified by the Adviser as having value characteristics. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Value Index. The Russell 2000^® Value Index is an unmanaged index that contains stocks from the Russell 2000^® Index with less than average growth orientation. As of November 30, 2019, the median market capitalization of this index was $666 million and the largest stock was $6.7 billion. Please note that this range is as of a particular point in time and is subject to change.

The Fund generally invests in the equity securities of small companies. The Adviser will seek to invest in companies it considers to be well managed and to have attractive fundamental financial characteristics. The Adviser believes greater potential for price appreciation exists among small companies since they tend to be less widely followed by other securities analysts and thus may be more likely to be undervalued by the market. The Fund may invest from time to time a portion of its assets, not to exceed 20% (under normal conditions) at the time of purchase, in companies with larger market capitalizations.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may also invest up to 25% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Small Cap Companies Risk. The Fund will invest in smaller issuers which are more volatile and less liquid than investments in issuers with a market capitalization greater than the market capitalization of companies in the Russell 2000^® Value Index. Small market capitalization issuers are not as diversified in their business activities as issuers with market capitalizations greater than the market capitalization of companies in the Russell 2000^® Value Index and are more susceptible to changes in the business cycle.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners Small Cap Value Fund II’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	14.78% (quarter ended December 31, 2010)
Worst Quarter:	-20.45% (quarter ended September 30, 2011)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Institutional Class Prospectus | Boston Partners Small Cap Value Fund II | Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

22.39%

5 Years

rr_AverageAnnualReturnYear05

6.99%

10 Years

rr_AverageAnnualReturnYear10

10.56%

Institutional Class Prospectus | Boston Partners Small Cap Value Fund II | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

BPSIX

Management Fees

rr_ManagementFeesOverAssets

0.95%

^[1]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.21%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.17%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.07%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.10%

One Year

rr_ExpenseExampleYear01

$ 1,121

Three Years

rr_ExpenseExampleYear03

3,647

Five Years

rr_ExpenseExampleYear05

6,369

Ten Years

rr_ExpenseExampleYear10

$ 14,142

Annual Return 2010

rr_AnnualReturn2010

18.50%

Annual Return 2011

rr_AnnualReturn2011

(3.43%)

Annual Return 2012

rr_AnnualReturn2012

22.87%

Annual Return 2013

rr_AnnualReturn2013

34.74%

Annual Return 2014

rr_AnnualReturn2014

4.21%

Annual Return 2015

rr_AnnualReturn2015

(4.33%)

Annual Return 2016

rr_AnnualReturn2016

25.97%

Annual Return 2017

rr_AnnualReturn2017

9.78%

Annual Return 2018

rr_AnnualReturn2018

(16.34%)

Annual Return 2019

rr_AnnualReturn2019

28.02%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

14.78%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(20.45%)

1 Year

rr_AverageAnnualReturnYear01

28.02%

5 Years

rr_AverageAnnualReturnYear05

7.22%

10 Years

rr_AverageAnnualReturnYear10

10.83%

Institutional Class Prospectus | Boston Partners Small Cap Value Fund II | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

27.26%

^[4]

5 Years

rr_AverageAnnualReturnYear05

6.12%

^[4]

10 Years

rr_AverageAnnualReturnYear10

10.18%

^[4]

Institutional Class Prospectus | Boston Partners Small Cap Value Fund II | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

17.07%

5 Years

rr_AverageAnnualReturnYear05

5.46%

10 Years

rr_AverageAnnualReturnYear10

8.87%

[1] Prior to October 1, 2019, the management fee was 1.00%.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.10% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Orinda | Orinda Income Opportunities Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — ORINDA INCOME OPPORTUNITIES FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Orinda Income Opportunities Fund (the “Fund”) seeks to maximize current income with potential for modest growth of capital.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund’s Class A shares. More information about these and other discounts is available from your financial professional and in the “Distribution of Fund Shares” section of the Fund’s Prospectus and the “Other Information Regarding Maximum Sales Charge, Purchases and Redemptions” section of the Fund’s Statement of Additional Information (“SAI”). Each financial intermediary may impose different sales charges and these variations are described in Appendix A of the Fund’s Prospectus.

Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 131% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

131.00%

Expense Breakpoint Discounts [Text]

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You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund's Class A shares.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in Class I Shares of the Fund and $10,000 in Class A and Class D Shares of the Fund (the minimum initial investment for Class A and Class D Shares is $5,000) for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that each year your investment has a 5% return and Fund operating expenses remain the same. Although your actual costs and returns might be different, your approximate costs of investing in the Fund would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund will attempt to achieve its investment objective by investing in U.S. and non-U.S. securities and investment instruments including, but not limited to, equity securities, debt securities, and derivatives. The Fund’s allocation to these various security types and asset classes will vary over time in response to changing market opportunities with the goal of maximizing current income.

The Fund may invest without limit in equity securities of issuers of any market capitalization. The types of equity securities in which the Fund will generally invest include common stocks, preferred stocks, real estate investment trusts (“REITs”), master limited partnerships (“MLPs”), rights, warrants, depositary receipts and other investment companies, including exchange-traded funds (“ETFs”). The Fund’s equity investments may also take the form of depositary receipts including American Depositary Receipts (“ADRs”), European Depositary Receipts (“EDRs”) and Global Depositary Receipts (“GDRs”). The Fund generally invests in dividend paying stocks. The Fund may invest up to 25% of its net assets in initial public offerings (“IPOs”). The Fund may also invest without limit in foreign securities, including up to 50% of its net assets in securities of issuers located in emerging markets.

The Fund will generally invest at least 50% of its net assets in REITs. As a result of its investments in REITs, the Fund will be concentrated in the real estate industry. The Fund may invest in “Rule 144A” securities, which are privately placed, restricted securities that may only be resold under certain circumstances to other qualified institutional buyers.

The Fund may invest without limit in debt securities, provided that no more than 30% of its net assets are invested in debt securities rated below investment grade (known as “junk bonds”). The types of debt securities in which the Fund may invest generally include instruments and obligations of U.S. and non-U.S. corporate and other non-governmental entities, those of U.S. and non-U.S. governmental entities, mortgage-related or mortgage-backed securities (including “sub-prime” mortgages), asset-backed securities, exchange-traded notes (“ETNs”), floating rate loans, convertible securities, inflation-linked debt securities and subordinated debt securities. The Fund invests in debt securities with a broad range of maturities and the Fund’s investments may have fixed or variable principal payments.

The Fund may invest up to 85% of its net assets in derivatives, including options, futures (such as bond, index, interest rate and currency futures, but excluding commodities futures) and swaps (such as credit-default swaps, interest rate swaps and total return swaps). These derivative instruments may be used for investment purposes, to modify or hedge the Fund’s exposure to a particular investment market related risk, to manage the volatility of the Fund, to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates and as a substitute for purchasing or selling securities.

The Fund may utilize leverage (by borrowing against a line of credit for investment purposes) up to one-third of the value of its assets as part of the portfolio management process. The Fund may also sell securities short with respect to 100% of its net assets and may lend its portfolio securities to generate additional income. A short sale is the sale by the Fund of a security that it does not own in anticipation of purchasing the same security in the future at a lower price to close the short position.

The Fund will sell (or close a position in) a security when Orinda Asset Management LLC (the “Adviser”) determines that a particular security has achieved its investment expectations or the reasons for maintaining that position are no longer valid. It is expected that the Fund will have a portfolio turnover in excess of 100% on an annual basis. The Fund’s investment strategies may periodically result in a significant portion of its assets being invested in the securities of companies in the same sector of the market.

The Adviser may also invest up to 100% of the Fund’s total assets in cash, money-market instruments, bank obligations and other high-quality debt securities for temporary defensive purposes.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

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Losing all or a portion of your investment is a risk of investing in the Fund. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Bond Risk. Convertible bonds are hybrid securities that have characteristics of both bonds and common stocks and are therefore subject to both debt security risks and equity risk. Convertible bonds are subject to equity risk especially when their conversion value is greater than the interest and principal value of the bond. The prices of equity securities may rise or fall because of economic or political changes and may decline over short or extended periods of time.

● Credit Risk. The issuers of the bonds and other debt securities held by the Fund may not be able to make interest or principal payments. The degree of credit risk depends on the issuer’s financial condition and on the terms of the securities.

● Currency Risk. Changes in foreign currency exchange rates will affect the value of what the Fund owns and the Fund’s share price. Generally, when the U.S. dollar rises in value against a foreign currency, an investment in that country loses value because that currency is worth fewer U.S. dollars. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. Currency markets generally are not as regulated as securities markets.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Depositary Receipt Risk. Depositary receipts may be purchased through “sponsored” or “unsponsored” facilities. A sponsored facility is established jointly by the issuer of the underlying security and a depositary, whereas a depositary may establish an unsponsored facility without participation by the issuer of the depositary security. Holders of unsponsored depositary receipts generally bear all the costs of such facilities and the depositary of an unsponsored facility frequently is under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through voting rights to the holders of such receipts of the deposited securities. In addition, investment in ADRs, EDRs and GDRs may be less liquid than the underlying shares in their primary trading market.

● Derivatives Risk. The Fund’s use of derivatives (which may include options, futures and swaps, among others) may reduce the Fund’s returns and/or increase volatility. Derivatives involve the risk of improper valuation, the risk of ambiguous documentation, and the risk that changes in the value of the derivative may not correlate perfectly with the underlying security. Derivatives are also subject to market risk, interest rate risk, credit risk, counterparty risk and liquidity risk. Derivatives may be more sensitive to changes in economic or market conditions than other types of investments and could result in losses that significantly exceed the Fund’s original investment.

● Exchange-Traded Fund and Mutual Fund Risk. When the Fund invests in an ETF or mutual fund, it will bear additional expenses based on its pro rata share of the ETFs or mutual fund’s operating expenses, including the potential duplication of management fees. The risk of owning an ETF or mutual fund generally reflects the risks of owning the underlying securities the ETF or mutual fund holds. The Fund also will incur brokerage costs when it purchases ETFs. Index ETFs may not track their underlying indices.

● Exchange-Traded Note Risk. The value of an ETN may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in the underlying securities’ markets, changes in the applicable interest rates, changes in the issuer’s credit rating and economic, legal, political or geographic events that affect the referenced index. In addition, the notes issued by ETNs and held by the Fund are unsecured debt of the issuer.

● Fixed Income Securities Risk. Fixed income securities are subject to interest rate risk and credit risk. There is also the risk that an issuer may “call,” or repay, its high yielding bonds before their maturity dates.

● Foreign and Emerging Market Securities Risk. Foreign investments may carry risks associated with investing outside the United States, such as currency fluctuation, economic or financial instability, lack of timely or reliable financial information or unfavorable political or legal developments. Those risks are increased for investments in emerging markets.

● Futures Risk. The value of a futures contract tends to increase and decrease in correlation with the value of the underlying instrument. Risks of futures contracts may arise from an imperfect correlation between movements in the price of the futures and the price of the underlying instrument. The Fund’s use of futures contracts (and related options) exposes the Fund to leverage risk because of the small margin requirements relative to the value of the futures contract. While futures contracts are generally liquid instruments, under certain market conditions they may become illiquid. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures could exceed the Fund’s initial investment in such contracts.

● Government-Sponsored Entities Risk. Securities issued by government-sponsored entities may not be backed by the full faith and credit of the United States.

● High-Yield Securities Risk. Fixed income securities that are rated below investment grade (i.e., “junk bonds”) are subject to additional risk factors due to the speculative nature of these securities, such as increased possibility of default liquidation of the security, and changes in value based on public perception of the issuer.

● Initial Public Offering Risk. The market value of IPO shares may fluctuate considerably due to factors such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk.

● Interest Rate Risk. The market value of fixed income securities changes in response to interest rate changes and other factors. Generally, prices of fixed income securities will increase as interest rates fall and will decrease as interest rates rise. It is likely there will be less governmental action in the near future to maintain low interest rates. The negative impact on fixed income securities from the resulting rate increases for that and other reasons could be swift and significant.

● Large Companies Risk. The securities of large capitalization companies may underperform other segments of the market because such companies may be less responsive to competitive challenges and opportunities and may be unable to attain or maintain high growth rates during periods of economic expansion.

● Leverage and Short Sales Risk. Leverage is the practice of borrowing money to purchase securities. If the securities decrease in value, the Fund will suffer a greater loss than would have resulted without the use of leverage. A short sale will be successful if the price of the shorted security decreases, however, if the underlying security goes up in price during the period in which the short position is outstanding, the Fund will realize a loss. The risk on a short sale is unlimited because the Fund must buy the shorted security at the higher price to complete the transaction. Therefore, short sales may be subject to greater risks than investments in long positions.

● Management Risk. The skill of the Adviser will play a significant role in the Fund’s ability to achieve its investment objective. The Fund’s ability to achieve its investment objective depends on the investment skill and ability of the Adviser and on its ability to correctly identify economic trends.

● Market Risk. The value of the Fund’s shares will fluctuate as a result of the movement of the overall stock market or the value of the individual securities held by the Fund, and you could lose money.

● Master Limited Partnership Risk. Investments in securities (units) of MLPs involve risks that differ from an investment in common stock. To the extent that an MLP’s interests are all in a particular industry, the MLP will be negatively impacted by economic events adversely impacting that industry. Additionally, holders of the units of MLPs have more limited control and limited rights to vote on matters affecting the partnership. There are also certain tax risks associated with an investment in units of MLPs.

● Mortgage-Related and Other Asset-Backed Securities Risk. Generally, rising interest rates tend to extend the duration of fixed rate mortgage-related securities, making them more sensitive to changes in interest rates. As a result, in a period of rising interest rates, if the Fund holds mortgage-related securities, it may exhibit additional volatility. This is known as extension risk. In addition, adjustable and fixed rate mortgage-related securities are subject to prepayment risk. When interest rates decline, borrowers may pay off their mortgages sooner than expected. This can reduce the returns of the Fund because it may have to reinvest that money at the lower prevailing interest rates. The risk of default is generally higher in mortgage-related investments that include sub-prime mortgages. Asset-backed securities are subject to risks similar to those associated with mortgage-related securities.

● Options Risk. Purchasing and writing put and call options are highly specialized activities and entail greater than ordinary investment risks. The Fund may not fully benefit from or may lose money on an option if changes in its value do not correspond as anticipated to changes in the value of the underlying securities.

● Portfolio Turnover Risk. A high portfolio turnover rate (100% or more on an annualized basis) increases the Fund’s transaction costs (including brokerage commissions and dealer costs), which adversely impacts the Fund’s performance. Higher portfolio turnover may result in the realization of more short-term capital gains than if the Fund had lower portfolio turnover.

● Preferred Stock Risk. Preferred stocks may be more volatile than fixed income securities and are more correlated with the issuer’s underlying common stock than fixed income securities. Additionally, the dividend on a preferred stock may be changed or omitted by the issuer.

● Real Estate and REIT Concentration Risk. The Fund is vulnerable to the risks of the real estate industry, such as the risk that a decline in rental income may occur because of extended vacancies, the failure to collect rents, increased competition from other properties, or poor management. The value and performance of REITs depends on how well the underlying properties owned by the REIT are managed. In addition, the value of an individual REIT’s securities can decline if the REIT fails to continue qualifying for special tax treatment. Investments in REITs may involve duplication of management fees and other expenses.

● Rule 144A Securities Risk. The market for Rule 144A securities typically is less active than the market for publicly-traded securities. Rule 144A securities carry the risk that the liquidity of these securities may become impaired, making it more difficult for the Fund to sell these bonds.

● Sector Risk. To the extent the Fund invests a significant portion of its assets in the securities of companies in the same sector of the market, the Fund is more susceptible to economic, political, regulatory and other occurrences influencing those sectors.

● Small and Medium Companies Risk. Investing in securities of small and medium capitalization companies may involve greater volatility than investing in larger and more established companies because small and medium capitalization companies can be subject to more abrupt or erratic share price changes than larger, more established companies.

● Swaps Risk. In a swap transaction, one party agrees to pay the other party an amount equal to the return, based upon an agreed-upon notional value, of a defined underlying asset or a non-asset reference (such as an index) during a specified period of time. In return, the other party would make periodic payments based on a fixed or variable interest rate or on the return from a different underlying asset or non-asset reference based upon an agreed-upon notional value. Swaps could result in losses if the underlying asset or reference does not perform as anticipated. The value of swaps, like many other derivatives, may move in unexpected ways and may result in losses for the Fund. Such transactions can have the potential for unlimited losses.

Risk Lose Money [Text]

rr_RiskLoseMoney

Losing all or a portion of your investment is a risk of investing in the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The Fund was reorganized following the close of business on April 28, 2017, to acquire the assets and liabilities of the Orinda Income Opportunities Fund, a series of Advisors Series Trust (the “Predecessor Fund”), in exchange for shares of the Fund. Accordingly, the Fund is the successor to the Predecessor Fund, and the following performance information shown prior to May 1, 2017, is that of the Predecessor Fund. The Fund has an investment objective, strategies and policies substantially similar to the Predecessor Fund, which was also advised by the Adviser.

The following information provides some indication of the risks of investing in the Fund. The bar chart shows changes in the Class I performance from year to year. The table shows how the Fund’s average annual returns for 1-year, 5-year and since inception periods compare with those of broad measures of market performance. The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available at www.orindafunds.com or by calling the Fund toll-free at 1-855-467-4632 (855-4ORINDA).

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The table shows how the Fund's average annual returns for 1-year, 5-year and since inception periods compare with those of broad measures of market performance.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-855-467-4632 (855-4ORINDA)

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.orindafunds.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund's past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance of the Fund (for the periods reflected in the chart above):

Best Quarter:	13.63% (quarter ended March 31, 2019)
Worst Quarter:	-9.55% (quarter ended December 31, 2018)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns (For the periods ended December 31, 2019)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns were calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on your tax situation and may differ from those shown and after-tax returns shown are not relevant to those who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts ("IRAs").

Performance Table One Class of after Tax Shown [Text]

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After-tax returns are shown only for Class I; after-tax returns for Class A and Class D will vary, to the extent each class has different expenses.

Performance Table Explanation after Tax Higher

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In certain cases, the figure representing "Return After Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund before taxes for the past calendar year, the past five calendar years, and since inception periods to the average annual total returns of a broad-based securities market index for the same periods.

Orinda | Orinda Income Opportunities Fund | Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

8.72%

5 Years

rr_AverageAnnualReturnYear05

3.05%

Since Inception

rr_AverageAnnualReturnSinceInception

3.32%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 28, 2013

Orinda | Orinda Income Opportunities Fund | Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

8.72%

5 Years

rr_AverageAnnualReturnYear05

3.05%

Since Inception

rr_AverageAnnualReturnSinceInception

3.35%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 27, 2013

Orinda | Orinda Income Opportunities Fund | Class I

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

OIOIX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

1.00%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.29%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.12%

^[3]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.91%

^[3]

One Year

rr_ExpenseExampleYear01

$ 1,940

Three Years

rr_ExpenseExampleYear03

6,000

Five Years

rr_ExpenseExampleYear05

10,316

Ten Years

rr_ExpenseExampleYear10

$ 22,327

Annual Return 2014

rr_AnnualReturn2014

6.75%

Annual Return 2015

rr_AnnualReturn2015

(2.90%)

Annual Return 2016

rr_AnnualReturn2016

9.51%

Annual Return 2017

rr_AnnualReturn2017

6.79%

Annual Return 2018

rr_AnnualReturn2018

(8.32%)

Annual Return 2019

rr_AnnualReturn2019

20.95%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2019

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.63%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.55%)

1 Year

rr_AverageAnnualReturnYear01

20.95%

5 Years

rr_AverageAnnualReturnYear05

4.72%

Since Inception

rr_AverageAnnualReturnSinceInception

4.78%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 28, 2013

Orinda | Orinda Income Opportunities Fund | Class I | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

19.19%

^[4]

5 Years

rr_AverageAnnualReturnYear05

2.82%

^[4]

Since Inception

rr_AverageAnnualReturnSinceInception

2.83%

^[1],[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 28, 2013

^[4]

Orinda | Orinda Income Opportunities Fund | Class I | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

12.79%

^[5]

5 Years

rr_AverageAnnualReturnYear05

2.96%

^[5]

Since Inception

rr_AverageAnnualReturnSinceInception

2.97%

^[1],[5]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 28, 2013

^[5]

Orinda | Orinda Income Opportunities Fund | Class A

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

OIOAX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.00%

Management Fees

rr_ManagementFeesOverAssets

1.00%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.33%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.12%

^[3]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.16%

^[3]

One Year

rr_ExpenseExampleYear01

$ 708

Three Years

rr_ExpenseExampleYear03

1,142

Five Years

rr_ExpenseExampleYear05

1,601

Ten Years

rr_ExpenseExampleYear10

$ 2,868

1 Year

rr_AverageAnnualReturnYear01

14.59%

5 Years

rr_AverageAnnualReturnYear05

3.34%

Since Inception

rr_AverageAnnualReturnSinceInception

3.64%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 28, 2013

Orinda | Orinda Income Opportunities Fund | Class D

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

OIODX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

1.00%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses

rr_OtherExpensesOverAssets

0.28%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.12%

^[3]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.92%

^[3]

One Year

rr_ExpenseExampleYear01

$ 295

Three Years

rr_ExpenseExampleYear03

904

Five Years

rr_ExpenseExampleYear05

1,538

Ten Years

rr_ExpenseExampleYear10

$ 3,242

1 Year

rr_AverageAnnualReturnYear01

19.71%

5 Years

rr_AverageAnnualReturnYear05

3.71%

Since Inception

rr_AverageAnnualReturnSinceInception

3.92%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 27, 2013

[1] The Predecessor Fund's Class I and Class A shares commenced operations on June 28, 2013.

[2] The Predecessor Fund's Class D shares commenced operations on September 27, 2013.

[3] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses.

[4] After-tax returns were calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown and after-tax returns shown are not relevant to those who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts ("IRAs"). After-tax returns are shown only for Class I; after-tax returns for Class A and Class D will vary, to the extent each class has different expenses.

[5] In certain cases, the figure representing "Return After Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Summit Global Investments | SGI U.S. Small Cap Equity Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION     U.S. Small Cap Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The SGI U.S. Small Cap Equity Fund (for this section only, the “Fund”) seeks to outperform the Russell 2000^® Index over a market cycle while reducing overall volatility. There can be no guarantee that the Fund will achieve its investment objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information — Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information — Reducing or Eliminating the Front-End Sales Charge.” Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)      

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. For the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 145% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

145.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Class A Shares or Class C Shares or $1,000,000 in the Class I Shares of the Fund and for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund will invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities, primarily common stocks of U.S. issuers with small market capitalizations. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Index. The Russell 2000^® Index is a small cap stock market index measuring the performance of approximately 2,000 small cap U.S. companies. As of November 30, 2019, the median market capitalization of this index was $786 million and the largest stock was $9.1 billion. The Fund’s investments will generally consist of securities, which may include common stocks, preferred stocks, warrants to acquire common stock, and securities convertible into common stock. The Fund purchases equity securities traded in the U.S. on registered exchanges or the over-the-counter market. The Fund may also invest in other registered investment companies, including exchange-traded funds (“ETFs”), and may invest in real estate investment trusts (“REITs”).

The Adviser attempts to lower the Fund’s market risk by investing in U.S. equity securities that lower the overall volatility of the Fund’s portfolio as compared to the Russell 2000^® Index. Volatility is a statistical measurement of the magnitude of up and down fluctuations in the value of a financial instrument or index. The Fund invests in stocks that often exhibit less volatile stock price patterns, strengthening business metrics (i.e., earnings, debt, return on assets, competition, customers, industry, etc.) and quantitative factors such as earnings variability, leverage, volatility, price/book, price/cash flow, etc. In addition, the Adviser reviews the idiosyncratic risks associated with each stock if these risks are deemed elevated with increased downside risks, due to environmental, social and/or governance (“ESG”) issues. The Adviser selects securities for the Fund that it anticipates will produce a portfolio with less volatility with more capital protection and consistent returns. While the Adviser attempts to manage the Fund’s volatility, there is no guarantee that the strategy will be successful or that the Fund’s portfolio will not experience periods of volatility.

The Fund may sell a stock if the Adviser identifies fundamental, ESG, or legal risks and/or if the risk/return ranking declines due to increasing risk and/or decreasing return potential. The Fund may also decrease weight in an investment for risk control purposes.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Loss of money is a risk of investing in the Fund. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

■ Common Stock Risk. Investments in common stocks are subject to market, economic and business risks that will cause their price to fluctuate over time. Therefore, an investment in the Fund may be more suitable for long-term investors who can bear the risk of these fluctuations.

■ Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities

■ Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

■ Environmental, Social and Governance Investing Risk. ESG investing risk is the risk stemming from the environmental, social and governance factors that the Fund applies in selecting securities. The Fund intends to invest in companies with measurable high ESG ratings relative to their sector peers, and screen out particular companies that do not meet its ESG criteria. This may affect the Fund’s exposure to certain companies or industries and cause the Fund to forego certain investment opportunities. The Fund’s results may be lower than other funds that do not seek to invest in companies based on ESG ratings and/or screen out certain companies or industries. The Fund seeks to identify companies that it believes may have a societal impact outcome, but investors may differ in their views of what constitutes positive or negative societal impact outcomes. As a result, the Fund may invest in companies that do not reflect the beliefs and values of any particular investor.

■ High Portfolio Turnover Risk. The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions and cause higher levels of current tax liability to shareholders of the Fund. A portfolio turnover rate of 100% is considered to be high. The Adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

■ Investment Companies and ETFs Risk. Investing in other investment companies, including ETFs, may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. The risk of owning an investment company or ETF generally reflects the risks of owning the underlying investments the investment company or ETF holds. The Fund may incur brokerage fees in connection with its purchase of ETF shares. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

■ Low Volatility Risk. Although subject to the risks of common stocks, low volatility stocks are seen as having a lower risk profile than the overall markets. However, a portfolio comprised of low volatility stocks may not produce investment exposure that has lower variability to changes in such stocks’ price levels. Investing in low volatility stocks may limit the Fund’s gains in rising markets.

■ Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

■ Market Risk. The NAV of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes will produce less volatility, there is no guarantee that the stocks will perform as expected.

■ Opportunity Risk. As with all mutual funds, the Fund is subject to the risk of missing out on an opportunity because the assets necessary to take advantage of it are tied up in less advantageous investments.

■ REITs Risk. The Fund’s investments in REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidating interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings, and may be subject to more abrupt or erratic price movements than the securities of larger companies. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

■ Small Cap Risk. Stocks of small companies may be more volatile than, and not as readily marketable as, those of larger companies. Small companies may also have limited product lines, markets or financial resources and may be dependent on relatively small or inexperienced management groups. Additionally, the trading volume of small company securities may make them more difficult to sell than those of larger companies. Moreover, the lack of an efficient market for the securities may make them difficult to value.

■ Warrants Risk. The purchase of warrants involves the risk that the Fund could lose the purchase value of a warrant if the right to subscribe to additional shares is not executed prior to the warrant’s expiration. Also, the purchase of warrants involves the risk that the effective price paid for the warrant added to the subscription price of the related security may exceed the value of the subscribed security’s market price such as when there is no movement in the level of the underlying security.

Risk Lose Money [Text]

rr_RiskLoseMoney

Loss of money is a risk of investing in the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The chart below illustrates the performance of the Fund’s Class I Shares. The information shows the Fund’s performance for one year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information may be obtained at www.sgiam.com or by calling 1-855-744-8500.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information shows the Fund's performance for one year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-855-744-8500

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.sgiam.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31 *

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

Sales charges (loads) or account fees are not reflected in the bar chart and if these amounts were reflected, returns would be less than those shown.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

^* The returns in the bar chart are for Class I Shares. Class A Shares and Class C Shares would have substantially similar annual returns because each class of shares would have invested in the same portfolio of securities, and the annual returns would differ only to the extent that the classes have different expenses. The Fund’s Class A Shares are subject to a sales charge (load). Sales charges (loads) or account fees are not reflected in the bar chart and if these amounts were reflected, returns would be less than those shown.

Best and Worst Quarterly Performance (for the period reflected in the chart above):

Best Quarter: 10.94% (quarter ended March 31, 2019)
Worst Quarter: -19.35% (quarter ended December 31, 2018)

Performance Table Heading

rr_PerformanceTableHeading

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The table below, which includes all applicable sales charges (loads) and account fees, compares the Fund's Class I, Class A and Class C Shares average annual total returns for the periods indicated to the average annual total returns of a broad-based securities market index for the same periods.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs").

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below, which includes all applicable sales charges (loads) and account fees, compares the Fund’s Class I, Class A and Class C Shares average annual total returns for the periods indicated to the average annual total returns of a broad-based securities market index for the same periods. Past performance (before and after taxes) is not necessarily an indicator of how the Fund will perform in the future.

Summit Global Investments | SGI U.S. Small Cap Equity Fund | Russell 2000® Index (reflects reinvestment of dividends and no deductions for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

25.52%

Since Inception

rr_AverageAnnualReturnSinceInception

12.91%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

Summit Global Investments | SGI U.S. Small Cap Equity Fund | Class I Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

SCLVX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.95%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.45%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.52%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.92%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.17%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.75%

One Year

rr_ExpenseExampleYear01

$ 17,784

Three Years

rr_ExpenseExampleYear03

58,663

Five Years

rr_ExpenseExampleYear05

102,098

Ten Years

rr_ExpenseExampleYear10

$ 222,948

Annual Return 2017

rr_AnnualReturn2017

8.71%

Annual Return 2018

rr_AnnualReturn2018

(9.86%)

Annual Return 2019

rr_AnnualReturn2019

20.66%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2019

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

10.94%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(19.35%)

1 Year

rr_AverageAnnualReturnYear01

20.66%

Since Inception

rr_AverageAnnualReturnSinceInception

10.30%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

Summit Global Investments | SGI U.S. Small Cap Equity Fund | Class I Shares | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

20.32%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

8.91%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

^[3]

Summit Global Investments | SGI U.S. Small Cap Equity Fund | Class I Shares | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

12.42%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

7.69%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

^[3]

Summit Global Investments | SGI U.S. Small Cap Equity Fund | Class A Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

LVSMX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.25%

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[4]

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.95%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.45%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.52%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.17%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.17%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.00%

One Year

rr_ExpenseExampleYear01

$ 717

Three Years

rr_ExpenseExampleYear03

1,153

Five Years

rr_ExpenseExampleYear05

1,614

Ten Years

rr_ExpenseExampleYear10

$ 2,884

1 Year

rr_AverageAnnualReturnYear01

14.06%

^[5]

Since Inception

rr_AverageAnnualReturnSinceInception

8.51%

^[5]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

^[5]

Summit Global Investments | SGI U.S. Small Cap Equity Fund | Class C Shares

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

SMLVX

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (Load)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Maximum Sales Charge (Load) Imposed on Reinvested Dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption Fee (as a percentage of amount redeemed, if applicable)

rr_RedemptionFeeOverRedemption

none

Management Fees

rr_ManagementFeesOverAssets

0.95%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses

rr_OtherExpensesOverAssets

0.45%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.52%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.92%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.17%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.75%

One Year

rr_ExpenseExampleYear01

$ 278

Three Years

rr_ExpenseExampleYear03

888

Five Years

rr_ExpenseExampleYear05

1,523

Ten Years

rr_ExpenseExampleYear10

$ 3,230

1 Year

rr_AverageAnnualReturnYear01

19.43%

Since Inception

rr_AverageAnnualReturnSinceInception

9.23%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses.

[2] Summit Global Investments, LLC (the "Adviser"), the Fund's investment adviser, has contractually agreed to waive management fees and reimburse expenses through February 28, 2021 to the extent that Total Annual Fund Operating Expenses (excluding certain items discussed below) exceed 1.23%, 1.48% and 2.23% of the Fund's average daily net assets attributable to Class I Shares, Class A and Class C Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and are expected to cause net Total Annual Fund Operating Expenses to exceed 1.23%, 1.48% or 2.23%, as applicable: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation may not be terminated before February 28, 2021 without the approval of the Board of Directors of The RBB Fund, Inc. (the "Company"). If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.23%, 1.48% and 2.23% of the Fund's average daily net assets attributable to Class I Shares, Class A Shares and Class C Shares, respectively, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs"). Class I Shares, Class A Shares and Class C Shares commenced operations on March 31, 2016.

[4] A contingent deferred sales charge of 1.00% is assessed on certain redemptions of Class A Shares made within 18 months after purchase where no initial sales charge was paid at the time of purchase as part of an investment of $1,000,000 or more.

[5] Effective as of January 1, 2018, Class A Shares of the Fund are charged a 5.25% sales load. Accordingly, performance information for Class A Shares for periods prior to January 1, 2018 has been restated to reflect the effect of the sales load.

XML

Total

Matson Money | Matson Money U.S. Equity VI Portfolio

MATSON MONEY U.S. EQUITY VI PORTFOLIO FMVUX

Investment Objective

The Matson Money U.S. Equity VI Portfolio (for this section only, the “Portfolio”) seeks long-term capital appreciation.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Portfolio. This table does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, overall fees and expenses would be higher.

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Matson Money Matson Money U.S. Equity VI Portfolio Institutional Class
Management Fees	0.50%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.26%
Acquired fund fees and expenses	0.29%	[1]
Total Annual Fund Operating Expenses	1.05%

Example

This Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. This Example does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, the costs shown below would be higher.

The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Matson Money | Matson Money U.S. Equity VI Portfolio | Institutional Class | USD ($)	107	334	579	1,281

Portfolio Turnover

The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Portfolio shares are held in a taxable account. These costs, which are not reflected in Total Annual Portfolio Operating Expenses or in the Example, affect the Portfolio’s performance. During the fiscal year ended August 31, 2019, the Portfolio’s portfolio turnover rate was 17% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Portfolio pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in equity securities, such as common stocks, preferred stocks or securities convertible into stocks, of U.S. companies, or invest substantially all of their assets in such equity securities. The Portfolio will diversify its investments by investing primarily in investment companies focusing on different segments of the equity markets, including large (“large-cap”), small (“small-cap”) and micro-capitalization (“micro-cap”) equity securities that the Portfolio’s investment adviser (“Adviser”) believes offer the prospect of long-term capital appreciation. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Portfolio’s net assets to be invested in the securities of investment companies, including other investment companies funded by insurance company separate accounts, that invest in the types of securities described in each asset class below, with less than 2% of the net assets invested in cash or money market instruments.

U.S. Large Cap Value Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of large cap companies that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time. Large cap companies are generally considered companies whose market capitalizations are generally in the highest 90% of total market capitalization or companies whose market capitalizations are larger than or equal to the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions.

U.S. Small Cap Value Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of small cap companies that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time. Small cap companies are generally considered companies whose market capitalizations are generally in the lowest 10% of total market capitalization or companies whose market capitalizations are smaller than the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions.

U.S. Large Company Asset Class: The underlying investment companies generally will purchase all of the stocks that comprise the S&P 500^® Index in approximately the proportions they are represented in the S&P 500^® Index. Generally, these are the U.S. stocks with the largest market capitalizations and, as a group, they represent approximately 80% of the total market capitalization of all publicly traded U.S. stocks.

U.S. Small Cap Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of small cap companies primarily based on market capitalization. Small cap companies are generally considered companies whose market capitalizations are generally in the lowest 10% of total market capitalization or companies whose market capitalizations are smaller than the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions. There may be some overlap in the companies in which the U.S. small cap asset class and the U.S. micro cap asset class invest.

U.S. Micro Cap Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of micro cap companies. Micro cap companies are generally considered companies whose market capitalizations are generally in the lowest 5% of total market capitalization or companies whose market capitalizations are smaller than the 1,500th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions. There may be some overlap in the companies in which the U.S. micro cap asset class and the U.S. small cap asset class invest.

The underlying investment companies may use derivatives, such as futures contracts and options on futures contracts for U.S. equity securities and indices, to adjust market exposure based on actual or expected cash inflows to or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, options and swaps to help the ETF track its underlying index.

The Portfolio reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Portfolio employs a temporary defensive measure, the Portfolio may not achieve its investment objective. Periodically the Adviser will review the allocations for the Portfolio in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Portfolio in the underlying investment companies without notice to shareholders or the holders of the variable annuity or variable life insurance policies.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Portfolio, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Portfolio, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Stocks of large cap, small cap or micro cap companies in which the Portfolio’s underlying investment companies invest or in which the Portfolio invests directly may temporarily fall out of favor with investors or may be more volatile than the rest of the U.S. market as a whole.

● The smaller the capitalization of a company, generally the less liquid its stock and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records and are more likely to fail than companies with larger market capitalizations.

● Although the Portfolio will invest in other investment companies that follow a value oriented strategy, value stocks may perform differently from the market as a whole and such a strategy may cause the Portfolio at times to underperform equity funds that use other investment strategies.

● Companies in which the Portfolio’s underlying investment companies invest may suffer unexpected losses or lower than expected earnings or their securities may become difficult or impossible to sell at the time and for the price that the underlying investment adviser(s) would like.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Portfolio could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Portfolio invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in U.S. equity securities, the NAV of the Portfolio will change with changes in the share prices of the investment companies in which the Portfolio invests.

● There is a risk that large, small or micro capitalization stocks may not perform as well as other asset classes or the U.S. stock market as a whole. In the past, large, small and micro capitalization stocks have gone through cycles of doing better or worse than the stock market in general.

● There is a risk that the Portfolio, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Portfolio will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. the Portfolio may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Cyber security risk is the risk of an unauthorized breach and access to Portfolio assets, Portfolio or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Portfolio, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Portfolio investors from purchasing, redeeming or exchanging shares or receiving distributions. The Portfolio and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Portfolio or its service providers may adversely impact and cause financial losses to the Portfolio or its shareholders.

More information about the Portfolio’s investments and risks is contained under the section entitled “More About Each Portfolio’s Investments and Risks.”

Performance Information

The chart below illustrates the performance of the Portfolio. The information shows you how the Portfolio’s performance has varied year by year and provides some indication of the risks of investing in the Portfolio. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 11.66% (quarter ended March 31, 2019)

Worst Quarter: -17.62% (quarter ended December 31, 2018)

Average Annual Total Returns for the Periods Ended December 31, 2019

The following table compares the average annual total returns of the Portfolio before and after taxes for the past calendar year, the past five calendar years, and since inception to the average total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Matson Money - Matson Money U.S. Equity VI Portfolio		1 Year	5 Years	Since Inception	Inception Date
Institutional Class		22.69%	7.07%	7.30%	Feb. 18, 2014
Institutional Class | After Taxes on Distributions	[1]	21.11%	5.73%	6.14%	Feb. 18, 2014
Institutional Class | After Taxes on Distributions and Sales		14.53%	5.36%	5.61%	Feb. 18, 2014
Russell 2500® Index (reflects no deduction for fees, expenses or taxes)		27.77%	8.93%	9.17%	Feb. 18, 2014
Composite Index	[2]	26.63%	8.85%	9.60%	Feb. 18, 2014

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Portfolio incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Portfolio Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] The Composite Index is comprised of the S&P 500® Index, Russell 1000® Value Index, Russell 2000® Index and Russell 2000® Value Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Portfolio's Investments and Risks."

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Matson Money | Free Market International Equity Fund

FREE MARKET INTERNATIONAL EQUITY FUND FMNEX

Investment Objective

The Free Market International Equity Fund (for this section only, the “Fund”) seeks long-term capital appreciation.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Matson Money Free Market International Equity Fund Institutional Class
Management Fees	0.49%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.09%
Acquired fund fees and expenses	0.43%	[1]
Total Annual Fund Operating Expenses	1.01%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Matson Money | Free Market International Equity Fund | Institutional Class | USD ($)	103	322	558	1,236

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 4% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in equity securities, such as common stocks, preferred stocks or securities convertible into stocks, of foreign companies, or invest substantially all of their assets in such equity securities. The Fund will diversify its investments by investing primarily in investment companies that focus on different segments of the foreign equity markets, including emerging markets, with little or no focus on domestic equity markets. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Fund’s net assets to be invested in the securities of investment companies that invest in the types of securities described in each asset class below, with less than 5% of the net assets invested in cash or money market instruments.

International Small Cap Value Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of small companies in foreign countries with developed markets that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios, as well as economic conditions and developments in the issuer’s industry. The criteria used for assessing value are subject to change from time to time. The underlying investment adviser(s) determine the maximum market capitalization of a small company with respect to each country. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Large Cap Value Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of large companies in foreign countries with developed markets that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios, as well as economic conditions and developments in the issuer’s industry. The criteria used for assessing value are subject to change from time to time. The underlying investment adviser(s) determine the minimum market capitalization of a large company with respect to each country or region. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Small Company Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of small companies in foreign countries with developed markets. The underlying investment adviser(s) determine the maximum market capitalization of a small company with respect to each country. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Large Cap Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of large companies in foreign countries with developed markets. The underlying investment adviser(s) determine the minimum market capitalization of a large company with respect to each country or region. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

Emerging Markets Asset Class, Emerging Markets Value Asset Class, and Emerging Markets Small Cap Asset Class (collectively, the “Emerging Markets Asset Classes”): Underlying investment companies comprising each Emerging Markets Asset Class generally will purchase stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of companies located in emerging market countries, including frontier markets (emerging market countries in an earlier stage of development). The underlying investment companies investing in securities of the Emerging Markets Asset Class and the Emerging Markets Small Cap Asset Class will generally purchase the equity securities of larger and smaller companies, respectively, within each country. The underlying investment adviser(s) determine company size primarily based on market capitalization. The thresholds will vary by country or region, and the dollar amounts will change from time to time due to market conditions.

The underlying investment companies in the Emerging Markets Value Asset Class generally will purchase emerging market equity securities that are deemed by the underlying investment adviser(s) to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time.

The underlying investment companies may use derivatives, such as futures contracts and options on futures contracts for equity securities and indices, to hedge currency exposure or to adjust market exposure based on actual or expected cash inflows or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, forward currency contracts, options and swaps to help the ETF track its underlying index.

The Fund reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Fund employs a temporary defensive measure, the Fund may not achieve its investment objective. Periodically the Adviser will review the allocations for the Fund in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Fund in the underlying investment companies without notice to shareholders.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● The value of particular foreign equity securities which the Fund’s underlying investment companies may purchase or foreign stock markets on which the securities they may purchase are traded may decline in value.

● Stocks of large cap or small cap foreign companies in which the Fund’s underlying investment companies may invest may temporarily fall out of favor with investors or may be more volatile than particular foreign stock markets or foreign stock markets as a whole.

● The smaller the capitalization of a company, generally the less liquid its stock and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records and are more likely to fail than companies with larger market capitalizations.

● Stocks of large cap or small cap foreign companies in which the Fund’s underlying investment companies may invest may suffer unexpected losses or lower than expected earnings or such securities may become difficult or impossible to sell at the time and for the price the underlying investment advisers would like.

● Because the Fund owns shares of underlying investment companies that invest in foreign issuers, the Fund is subject to risks presented by investments in such issuers. Securities of foreign issuers may be negatively affected by political events, economic conditions, or inefficient, illiquid or unregulated markets in foreign countries. Foreign issuers may be subject to inadequate regulatory or accounting standards.

● Investments in emerging market securities by underlying investment companies in which the Fund invests are subject to higher risks than those in developed market countries because there is greater uncertainty in less established markets and economics. The foregoing risks may be greater in frontier markets, which are among the smallest and least mature investment markets.

● Currency risk is the risk that exchange rates for currencies in which securities held by the underlying investment companies in which the Fund invests are denominated will fluctuate daily. In general, the underlying investment companies do not hedge currency risk. As a result, if currencies in which foreign holdings are denominated depreciate against the U.S. Dollar, the value of your investment in the Fund may be adversely affected.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Fund could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Fund invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in equity securities of foreign companies, the NAV of the Fund will change with changes in the share prices of the investment companies in which the Fund invests.

● There is a risk that the Fund, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Fund will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

More information about the Fund’s investments and risks is contained under the section entitled “More About Each Fund’s Investments and Risks.”

Performance Information

The chart below illustrates the long-term performance of the Fund. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 17.69% (quarter ended September 30, 2010)

Worst Quarter: -22.38% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns of the Fund before and after taxes for the past calendar year, the past five calendar years and past ten calendar years to the average total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Matson Money - Free Market International Equity Fund		1 Year	5 Years	10 Years
Institutional Class		17.71%	4.86%	5.17%
Institutional Class | After Taxes on Distributions	[1]	17.12%	4.00%	4.42%
Institutional Class | After Taxes on Distributions and Sales		11.09%	3.66%	4.04%
MSCI World (excluding U.S.) Index (reflects no deduction expenses or taxes)		22.49%	5.42%	5.32%
Composite Index	[2]	21.10%	6.33%	5.77%

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] The Composite Index is comprised of the MSCI EAFE Index, MSCI EAFE Value Index, MSCI EAFE Small Cap Index, and MSCI Emerging Markets Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Fund's Investments and Risks."

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Matson Money | Matson Money Fixed Income VI Portfolio

MATSON MONEY FIXED INCOME VI PORTFOLIO FMVFX

Investment Objective

The Matson Money Fixed Income VI Portfolio (for this section only, the “Portfolio”) seeks total return (consisting of current income and capital appreciation).

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Portfolio. This table does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, overall fees and expenses would be higher.

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Matson Money Matson Money Fixed Income VI Portfolio Institutional Class
Management Fees	0.50%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.24%
Acquired fund fees and expenses	0.12%	[1]
Total Annual Fund Operating Expenses	0.86%

Example

This Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. This Example does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, the costs shown below would be higher.

The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Matson Money | Matson Money Fixed Income VI Portfolio | Institutional Class | USD ($)	88	274	476	1,058

Portfolio Turnover

The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Portfolio shares are held in a taxable account. These costs, which are not reflected in Total Annual Portfolio Operating Expenses or in the Example, affect the Portfolio’s performance. During the fiscal year ended August 31, 2019, the Portfolio’s portfolio turnover rate was 19% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Portfolio pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in fixed income securities that the Adviser believes offer the prospect of providing total return, or invest substantially all of their assets in such fixed income securities. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Portfolio’s net assets to be invested in the securities of investment companies, including other investment companies funded by insurance company separate accounts, that invest in the types of securities described in each asset class below, with less than 2% of the net assets invested in cash or money market instruments.

One-Year Fixed Income Asset Class: The underlying investment companies generally will purchase U.S. government obligations, U.S. government agency obligations, dollar-denominated obligations of foreign issuers issued in the U.S., securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the U.S., foreign government and agency obligations, bank obligations, including the obligations of U.S. subsidiaries and branches of foreign banks, corporate obligations, commercial paper, repurchase agreements, and obligations of supranational organizations such as the World Bank, the European Investment Bank and the Inter-American Development Bank. Generally, obligations comprising this asset class will mature within one year from the date of settlement, but substantial investments may be made in obligations maturing within two years from the date of settlement when greater returns are available.

Two-Year Global Fixed Income Asset Class: The underlying investment companies generally will purchase obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, corporate debt obligations, bank obligations, commercial paper, repurchase agreements, and other debt obligations of domestic and foreign issuers with maturities of no more than two years. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the underlying investment adviser(s) will focus investment in the longer-term area, otherwise, the underlying investment companies will focus investment in the shorter-term area of the eligible maturity range. Because many of the investments of the underlying investment companies in this asset class will be denominated in foreign currencies, the underlying investment companies may also enter into foreign currency forward contracts to attempt to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another.

Intermediate Government Fixed Income Asset Class: The underlying investment companies generally will purchase debt obligations of the U.S. government and U.S. government agencies. Generally, investment companies in the asset class will purchase securities with maturities of between five and fifteen years, however such investment companies ordinarily will have an average weighted maturity of between three and ten years. The underlying investment companies may invest a portion of their assets in the obligations of foreign governments. Those obligations at the time of purchase must be either rated in the highest rating category of a nationally recognized statistical rating organization or, in the case of any obligation that is unrated, of comparable quality.

Five-Year Global Fixed Income Asset Class: The underlying investment companies generally will purchase obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, corporate debt obligations, bank obligations, commercial paper, repurchase agreements, obligations of other domestic and foreign issuers, securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the United States, and obligations of supranational organizations. Generally, obligations comprising this asset class have a weighted average maturity not exceeding five years. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the underlying investment adviser(s) will focus investment in the longer-term area, otherwise, the underlying investment companies will focus investment in the shorter-term area of the eligible maturity range. Because many of the investments of the underlying investment companies in this asset class will be denominated in foreign currencies, the underlying investment companies may also enter into foreign currency forward contracts to attempt to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another.

Short-Term Corporate Bond Asset Class: The underlying investment companies generally will track the investment results of the ICE BofAML 1-5 Year US Corporate Index, which measures the performance of investment-grade corporate bonds of both U.S. and non- U.S. issuers that are U.S. dollar denominated and publicly issued in the U.S. domestic market and have a remaining maturity of greater than or equal to one year and less than five years.

Intermediate-Term Corporate Bond Asset Class: The underlying investment companies generally will track the investment results of the ICE BofAML 5-10 Year US Corporate Index, which measures the performance of investment-grade corporate bonds of both U.S. and non-U.S. issuers that are U.S. dollar denominated and publicly issued in the U.S. domestic market and have a remaining maturity of greater than or equal to five years and less than ten years.

Inflation Protected Securities Asset Class: The underlying investment companies generally will track the investment results of the Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L), which measures the performance of the inflation-protected public obligations of the U.S. Treasury, commonly known as “TIPS.” TIPS are securities issued by the U.S. Treasury that are designed to provide inflation protection to investors. TIPS are income-generating instruments whose interest and principal payments are adjusted for inflation - a sustained increase in prices that erodes the purchasing power of money. The inflation adjustment, which is typically applied monthly to the principal of the bond, follows a designated inflation index, the consumer price index (“CPI”), and TIPS’ principal payments are adjusted according to changes in the CPI. A fixed coupon rate is applied to the inflation-adjusted principal so that as inflation rises, both the principal value and the interest payments increase.

The underlying investment companies may also use derivatives, such as futures contracts and options on futures contracts for equity securities and indices, to hedge currency exposure or to adjust market exposure based on actual or expected cash inflows or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, forward currency contracts, options and swaps to help the ETF track its underlying index.

Certain underlying investment companies may concentrate their investments (invest more than 25% of its total assets) in obligations of U.S. and foreign banks and bank holding companies when the yield to maturity on eligible portfolio investments in banking securities as a group generally exceeds the yield to maturity on all other eligible portfolio investments as a group generally for a period of five consecutive days when the New York Stock Exchange (“NYSE”) is open for trading. While the Portfolio will not concentrate its investments in any one industry, the Portfolio may be focused on banking sectors under certain circumstances.

The Portfolio reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Portfolio employs a temporary defensive measure, the Portfolio may not achieve its investment objective. Periodically the Adviser will review the allocations for the Portfolio in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Portfolio in the underlying investment companies without notice to shareholders or the holders of the variable annuity or variable life insurance policies.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Portfolio, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Portfolio, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Fixed income securities in which the Portfolio’s underlying investment companies may invest are subject to certain risks, including: interest rate risk, reinvestment risk, prepayment and extension risk, credit/default risk, and the risks associated with investing in repurchase agreements.

● Interest rate risk involves the risk that prices of fixed income securities will rise and fall in response to interest rate changes.

● Reinvestment risk involves the risk that proceeds from matured investments may be re-invested at lower interest rates.

● Prepayment risk involves the risk that in declining interest rates environments prepayments of principal could increase and require the Portfolio to reinvest proceeds of the prepayments at lower interest rates.

● Extension risk involves the risk that prepayments of principal will decrease when interest rates rise resulting in a longer effective maturity of a security.

● Credit risk is the risk that the issuer of a security may be unable to make interest payments and/or repay principal when due. Credit risk also involves the risk that the credit rating of a security may be lowered.

● Repurchase agreement risk involves the risk that the other party to a repurchase agreement will be unable to complete the transaction and the underlying investment company in which the Portfolio invests may suffer a loss as a result.

● Because the Portfolio owns shares of underlying investment companies that invest in foreign issuers, the Portfolio is subject to risks presented by investments in such issuers. Securities of foreign issuers may be negatively affected by political events, economic conditions, or inefficient, illiquid or unregulated markets in foreign countries. Foreign issuers may be subject to inadequate regulatory or accounting standards.

● Currency risk is the risk that exchange rates for currencies in which securities held by the underlying investment companies in which the Portfolio invests are denominated will fluctuate daily. Forward foreign currency exchange contracts may limit potential gains from a favorable change in value between the U.S. dollar and foreign currencies. Unanticipated changes in currency pricing may result in poorer overall performance for the Portfolio than if it had not engaged in these contracts.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Portfolio could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Portfolio invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in fixed income securities, the NAV of the Portfolio will change with changes in the share prices of the investment companies in which the Portfolio invests.

● Not all obligations of U.S. government agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some are backed only by the credit of the issuing agency or instrumentality. Accordingly, there may be some risk of default by the issuer in such cases.

● There is a risk that the Portfolio, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Portfolio will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● Banks are very sensitive to changes in money market and general economic conditions. Adverse general economic conditions can cause financial difficulties for a bank’s borrowers and the borrowers’ failure to repay their loans can adversely affect the bank’s financial situation. Banks are subject to extensive regulation and decisions by regulators may limit the loans banks make and the interest rates and fees they charge, which could reduce bank profitability.

● Inflation protected securities, such as TIPS, generally will fluctuate in response to changes in real interest rates, generally decreasing when real interest rates rise and increasing when real interest rates fall. In addition, interest payments on inflation-protected securities will generally vary up or down along with the rate of inflation. Real interest rates are generally measured as a nominal interest less an inflation rate. As such, investors should be aware that an investment in TIPS over a particular timeframe may decrease in value even in an inflationary environment. There can be no assurance that the inflation index used will accurately measure the real rate of inflation in the prices of goods and services. Because of their inflation adjustment feature, inflation-protected bonds typically have lower yields than conventional fixed-rate bonds.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Portfolio may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Cyber security risk is the risk of an unauthorized breach and access to Portfolio assets, Portfolio or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Portfolio, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Portfolio investors from purchasing, redeeming or exchanging shares or receiving distributions. The Portfolio and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Portfolio or its service providers may adversely impact and cause financial losses to the Portfolio or its shareholders.

More information about the Portfolio’s investments and risks is contained under the section entitled “More About Each Portfolio’s Investments and Risks.”

Performance Information

The chart below illustrates the performance of the Portfolio. The information shows you how the Portfolio’s performance has varied year by year and provides some indication of the risks of investing in the Portfolio. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 1.89% (quarter ended March 31, 2019)

Worst Quarter: -1.33% (quarter ended December 31, 2016)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns of the Portfolio before and after taxes for the past calendar year, the past five calendar years, and since inception to the average total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Matson Money - Matson Money Fixed Income VI Portfolio		1 Year	5 Years	Since Inception	Inception Date
Institutional Class		4.52%	1.28%	1.12%	Feb. 18, 2014
Institutional Class | After Taxes on Distributions	[1]	3.82%	0.80%	0.67%	Feb. 18, 2014
Institutional Class | After Taxes on Distributions and Sales		2.68%	0.78%	0.67%	Feb. 18, 2014
FTSE World Government Bond Index 1-5 Years (reflects no deduction for fees, expenses or taxes)		3.86%	1.92%	1.87%	Feb. 18, 2014
Composite Index	[2]	5.34%	2.04%	2.03%	Feb. 18, 2014

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Portfolio incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] The Composite Index is comprised of the Three-Month Treasury Bill Index, Bloomberg Barclays Intermediate Government Bond Index, ICE BofAML 1-3 Year US Government/Corporate Index and Bloomberg Barclays U.S. Aggregate Bond Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Portfolio's Investments and Risks."

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Prospectus [Line Items]

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Document Type

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485BPOS

Document Period End Date

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Aug. 31, 2019

Entity Registrant Name

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RBB FUND, INC.

Entity Central Index Key

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0000831114

Entity Inv Company Type

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N-1A

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false

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Feb. 28, 2020

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Feb. 28, 2020

Prospectus Date

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Feb. 28, 2020

Investor Class Prospectus | Boston Partners All-Cap Value Fund

Prospectus [Line Items]

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Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — BOSTON PARTNERS ALL-CAP VALUE FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

Current income is a secondary objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 33% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

33.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers across the capitalization spectrum and identified by the Adviser as having value characteristics.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals, such as return on equity and earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may also invest up to 20% of its total assets in non U.S. dollar denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

The Fund may invest up to 10% of its net assets in securities that can be converted into common stock, such as certain debt securities and preferred stock.

The Fund may hedge overall portfolio exposure up to 40% of its net assets through the purchase and sale of index and individual put and call options.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may “cover” a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

● Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners All-Cap Value Fund’s Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Investor Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	13.26% (quarter ended December 31, 2011)
Worst Quarter:	-17.62% (quarter ended September 30, 2011)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund’s Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Investor Class Prospectus | Boston Partners All-Cap Value Fund | Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

26.26%

5 Years

rr_AverageAnnualReturnYear05

8.20%

10 Years

rr_AverageAnnualReturnYear10

11.71%

Investor Class Prospectus | Boston Partners All-Cap Value Fund | Investor Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

BPAVX

Management Fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.12%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.08%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.03%)

^[2]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.05%

One Year

rr_ExpenseExampleYear01

$ 107

Three Years

rr_ExpenseExampleYear03

287

Five Years

rr_ExpenseExampleYear05

483

Ten Years

rr_ExpenseExampleYear10

$ 1,048

Annual Return 2010

rr_AnnualReturn2010

13.19%

Annual Return 2011

rr_AnnualReturn2011

(1.62%)

Annual Return 2012

rr_AnnualReturn2012

15.61%

Annual Return 2013

rr_AnnualReturn2013

38.92%

Annual Return 2014

rr_AnnualReturn2014

11.98%

Annual Return 2015

rr_AnnualReturn2015

0.69%

Annual Return 2016

rr_AnnualReturn2016

14.52%

Annual Return 2017

rr_AnnualReturn2017

17.59%

Annual Return 2018

rr_AnnualReturn2018

(12.07%)

Annual Return 2019

rr_AnnualReturn2019

27.54%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.26%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(17.62%)

1 Year

rr_AverageAnnualReturnYear01

27.54%

5 Years

rr_AverageAnnualReturnYear05

8.75%

10 Years

rr_AverageAnnualReturnYear10

11.78%

Investor Class Prospectus | Boston Partners All-Cap Value Fund | Investor Class | After Taxes on Distributions

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

26.84%

^[3]

5 Years

rr_AverageAnnualReturnYear05

7.61%

^[3]

10 Years

rr_AverageAnnualReturnYear10

10.75%

^[3]

Investor Class Prospectus | Boston Partners All-Cap Value Fund | Investor Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

16.79%

5 Years

rr_AverageAnnualReturnYear05

6.71%

10 Years

rr_AverageAnnualReturnYear10

9.56%

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.05% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.05%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.05% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

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Value

Prospectus [Line Items]

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Document Type

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485BPOS

Document Period End Date

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Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

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0000831114

Entity Inv Company Type

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N-1A

Amendment Flag

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false

Document Creation Date

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Feb. 28, 2020

Document Effective Date

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Feb. 28, 2020

Prospectus Date

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Feb. 28, 2020

Institutional Class Prospectus | Boston Partners Emerging Markets Long/Short Fund

Prospectus [Line Items]

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Risk/Return [Heading]

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SUMMARY SECTION — BOSTON PARTNERS EMERGING MARKETS LONG/SHORT FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term growth of capital.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2022

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 186% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

186.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund will pursue its objective through investing in a non-diversified, multi-strategy long-short portfolio of equity securities and financial investments with equity like characteristics designed to provide exposure to emerging markets. Securities are selected by the Adviser using its "three circles" approach which combines a quantitative screening with a fundamental bottom up selection process. This investment strategy is grounded in the following principles: (1) low valuation stocks outperform high valuation stocks; (2) companies with strong fundamentals, e.g. high and sustainable returns on invested capital, outperform companies with weak fundamentals; and (3) stocks with positive business momentum, e.g. rising earnings estimates, outperform stocks with negative business momentum. With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Adviser examines various factors in determining the value characteristics of issuers, including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals, such as return-on-equity and earnings growth and cash flow.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in the securities of emerging market issuers, related derivative instruments and other investments that are tied economically to emerging market countries. The Adviser considers an emerging market country to include any country that is: 1) generally recognized to be an emerging market country by the international financial community, including the World Bank; 2) classified by the United Nations as a developing country; or 3) included in the MSCI Emerging Markets Index. Due to the unique relationship between China and its separately administered regions, the Adviser includes Hong Kong and Macau as emerging markets, independent of above definitions 1 through 3. The Adviser determines that an investment is tied economically to an emerging market if such investment satisfies one or more of the following conditions: 1) the issuer’s primary trading market is in an emerging market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in emerging markets; 3) the investment is included in an index representative of emerging markets; and 4) the investment is exposed to the economic risks and returns of emerging markets.

In managing the Fund’s portfolio, the Adviser will seek to identify mispriced publicly traded equity securities of emerging market companies including shorting securities that the Adviser believes will underperform and purchasing securities that the Adviser believes will outperform.

The long portion of the portfolio will emphasize low valuation, positive business momentum and high quality securities. The short portfolio will emphasize securities with high valuation risk, high balance sheet risk and signs of slowing sales and earnings momentum.

The Fund’s portfolio is rebalanced regularly to maintain the optimal risk/return trade-off. The Adviser assesses each stock’s changing characteristics relative to its contribution to portfolio risk. The Adviser will sell a stock held long or close out a short position in a stock that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

The equity securities in which the Fund will invest include equity securities issued by large-, mid- and small- or micro-cap companies, as well as exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers").

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by S&P Global, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded. The Fund will primarily invest in fixed income instruments, including high yield fixed income obligations, when the Fund believes that such instruments offer a better risk/reward profile than comparable equity opportunities.

Under normal circumstances, the Adviser expects that the Fund’s long positions will not exceed approximately 50% of the Fund’s net assets with a typical range of 30% to 70% net long.

The Fund’s long and short positions may involve (without limit) equity securities of non-U.S. issuers that are traded in the markets of the United States.

In addition to the short sales discussed above, the Fund may make short sales "against the box," a transaction in which the Fund enters into a short sale of a security which the Fund owns. The proceeds of the short sale will be held by a broker until the settlement date at which time the Fund delivers the security to close the short position. The Fund receives the net proceeds from the short sale. It is currently expected that the majority of the Fund’s short sales will not be against the box.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Fund is the sole shareholder of Boston Partners Emerging Markets Long/Short Offshore Ltd., a wholly-owned subsidiary organized under the laws of the Cayman Islands (the “Subsidiary”). Generally, the Subsidiary invests primarily in futures contracts traded on Indian stock exchanges. The Fund and its Subsidiary comply with the same fundamental investment restrictions on an aggregate basis, to the extent those restrictions are applicable to the investment activities of the Subsidiary. The Fund is the sole shareholder of its Subsidiary and does not expect shares of its Subsidiary to be offered or sold to other investors. An election has been made to cause the Subsidiary to be a disregarded entity for U.S. federal income tax purposes; accordingly, the assets and income of the Subsidiary will be treated for U.S. federal income tax purposes no differently from the other assets and income of the Fund.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund’s investments will be spread over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest in exchange traded funds to the extent permitted by the Investment Company Act of 1940, as amended (“1940 Act”), and applicable SEC orders.

The Fund may participate as a purchaser in initial public offerings of securities (“IPOs”). An IPO is a company’s first offering of stock to the public.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may also seek to increase its income by lending portfolio securities.

The Fund will invest in derivatives, including put and call options, futures, contracts for differences, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes. Contracts for differences offer exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin. The Fund’s investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, contracts for differences, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may not be successful in its strategy of taking long positions in securities the Adviser believes to be undervalued and short positions in securities the Adviser believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make. Investments the Fund makes may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund’s assets could impede portfolio management or the Fund’s ability to meet redemption requests or other current obligations.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling is speculative and also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund’s obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in the value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund’s loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

● Subsidiary Risks. By investing in the Subsidiary, the Fund is indirectly exposed to the risks associated with the Subsidiary’s investments. The derivatives and other investments held by the Subsidiary are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund. The Subsidiary is not registered under the 1940 Act, and, unless otherwise noted in this Prospectus, is not subject to all the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to continue to operate as it does currently and could adversely affect the Fund.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the long-term performance of the Fund. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

The Fund commenced operations as a series of The RBB Fund, Inc. on December 15, 2015, when substantially all of the assets of Boston Partners Emerging Markets Long/Short Equity (the “Prior Account”) transferred to the Fund. The Fund is managed in all material respects in a manner equivalent to the management of the Prior Account. Accordingly, the performance information shown below for periods prior to December 15, 2015 is that of the Prior Account. The Fund’s objectives, policies, guidelines and restrictions are in all material respects equivalent to the Prior Account. The Fund is managed by Joseph F. Feeney, Jr. and Paul Korngiebel, the same Prior Account portfolio managers that managed the Prior Account since its inception in 2015. The Prior Account was not registered under the Investment Company Act of 1940, as amended (“1940 Act”), and thus was not subject to certain investment and operational restrictions that are imposed by the 1940 Act. If the Prior Account had been registered under the 1940 Act, its performance may have been adversely affected. Accordingly, future Fund performance may be different than the Prior Account’s restated past performance. The Prior Account’s performance has been restated to reflect estimated expenses of the Fund. After-tax performance returns are not included for the Prior Account. The Prior Account was not a regulated investment company under Subchapter M of the Internal Revenue Code and therefore did not distribute current or accumulated earnings and profits and was not subject to the diversification and source of income requirements applicable to regulated investment companies.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	9.42% (quarter ended March 31, 2017)
Worst Quarter:	-8.82% (quarter ended December 31, 2018)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

Effective August 31, 2019, the Fund changed its primary index from the MSCI Emerging Markets Index - Gross Return to the MSCI Emerging Markets Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund's Institutional Class, including the Prior Account, both before and after taxes for the past calendar year and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Institutional Class Prospectus | Boston Partners Emerging Markets Long/Short Fund | MSCI® Emerging Markets Index - Net Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

18.42%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

5.01%

^[1],[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2015

^[1]

Institutional Class Prospectus | Boston Partners Emerging Markets Long/Short Fund | MSCI® Emerging Markets Index - Gross Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

18.88%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

5.41%

^[1],[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2015

^[1]

Institutional Class Prospectus | Boston Partners Emerging Markets Long/Short Fund | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

BELSX

Management Fees

rr_ManagementFeesOverAssets

1.50%

^[3]

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.59%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.06%

^[4]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.15%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.65%)

^[5]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.50%

One Year

rr_ExpenseExampleYear01

$ 1,526

Three Years

rr_ExpenseExampleYear03

6,104

Five Years

rr_ExpenseExampleYear05

10,947

Ten Years

rr_ExpenseExampleYear10

$ 24,315

Annual Return 2015

rr_AnnualReturn2015

(5.35%)

Annual Return 2016

rr_AnnualReturn2016

7.91%

Annual Return 2017

rr_AnnualReturn2017

24.78%

Annual Return 2018

rr_AnnualReturn2018

(18.30%)

Annual Return 2019

rr_AnnualReturn2019

17.46%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2017

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

9.42%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(8.82%)

1 Year

rr_AverageAnnualReturnYear01

17.46%

Since Inception

rr_AverageAnnualReturnSinceInception

4.25%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2015

Institutional Class Prospectus | Boston Partners Emerging Markets Long/Short Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

16.74%

^[6]

Since Inception

rr_AverageAnnualReturnSinceInception

2.83%

^[2],[6]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2015

^[6]

Institutional Class Prospectus | Boston Partners Emerging Markets Long/Short Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

10.60%

Since Inception

rr_AverageAnnualReturnSinceInception

2.69%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2015

[1] Effective August 31, 2019, the Fund changed its primary index from the MSCI Emerging Markets Index - Gross Return to the MSCI Emerging Markets Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

[2] The "Since Inception" performance includes performance from the Prior Account beginning on March 1, 2015 until the Fund's commencement of operations on December 15, 2015.

[3] Prior to October 1, 2019, the management fee was 1.85%.

[4] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[5] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 1.50% of the average daily net assets attributable to the Fund's Institutional Class shares. Because short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and/or expense reimbursements) are expected to exceed 1.50%. This contractual limitation is in effect until February 28, 2022 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.50% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[6] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Institutional Class Prospectus | Boston Partners Global Equity Advantage Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION - BOSTON PARTNERS GLOBAL EQUITY ADVANTAGE FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

December 31, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the period from the Fund’s inception on May 29, 2019 through the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 16% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

16.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other expenses" are estimated for the current fiscal year.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same (taking into account the contractual expense limitation until its expiration). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund seeks to achieve its investment objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity- related securities, including exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds (“ETFs”)), real estate investment trusts (“REITs”) and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% - unless market conditions are not deemed favorable by the Fund, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by a Co-Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Fund applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Fund considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer’s inherent value. The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities. The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund also seeks to diversify its overall portfolio by investing, under normal circumstances, up to 20% of its assets in the Campbell Advantage strategy, a systematic trend following program, which is diversified across global futures and forwards markets (types of derivative instruments). The Campbell Advantage strategy is designed to analyze market data to identify trends occurring within and across markets and asset classes globally. By trading four major asset classes (equity index futures, fixed income futures, commodities and foreign exchange), the portfolio composition is diverse and expected to maintain low correlation with equities over time. Additionally, portfolio risk is dynamically managed through a framework intended to maximize the Campbell Advantage strategy’s ability to complement the global long equity exposure in an attempt to limit the Fund’s downside risk during extended periods of high equity market volatility.

The Fund’s investments may include investments in registered and unregistered funds managed by Campbell or an affiliate to obtain exposure to the Campbell Advantage strategy. The Fund will invest in such affiliated funds only in accordance with the applicable restrictions of the 1940 Act, including Section 12(d)(1).

The Fund is “non-diversified” for purposes of the Investment Company Act of 1940, as amended, (the “1940 Act”) which means that the Fund may invest in fewer securities at any one time than a diversified fund. The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund’s Co-Advisers are Boston Partners and Campbell. Boston Partners is primarily responsible for managing the equity portion of the Fund’s portfolio, including equity securities and related derivative contracts. Campbell is primarily responsible for managing the Fund’s exposure to the Campbell Advantage strategy. Campbell is also primarily responsible for determining the allocation of the Fund’s portfolio between equity and other investments. Each Co-Adviser may also from time to time consult and work collaboratively with, or be informed by the decisions of or information from, one or both of the other Co-Advisers in connection with making certain investment decisions in regards to the Fund’s investment strategies and portfolio, in addition to various compliance, operational and administrative matters. While the Co-Advisers may work collaboratively in connection with the management of the Fund’s portfolio as described above, under certain circumstances, such as, for example, when certain personnel at another Co-Adviser are not available, a Co-Adviser may make decisions or otherwise act independently from the other Co-Advisers.

The Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Co-Advisers will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Active Management Risk. The Co-Advisers’ judgments about the attractiveness, value, or potential appreciation of the Fund’s investments may prove to be incorrect. The Fund could underperform in comparison to other funds with a similar benchmark or similar objectives and investment strategies if the Fund’s overall asset allocation, investment selections or strategies fail to produce the intended results.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Counterparty Risk. The derivative contracts entered into by the Fund may be privately negotiated in the over-the-counter market. These contracts also involve exposure to credit risk, since contract performance depends in part on the financial condition of the counterparty. Relying on a counterparty exposes the Fund to the risk that a counterparty will not settle a transaction in accordance with its terms and conditions because of a dispute over the terms of the contract (whether or not bona fide) or because of a credit or liquidity problem, thus causing the Fund to suffer a loss. If a counterparty defaults on its payment obligations to the Fund, this default will cause the value of an investment in the Fund to decrease. In addition, to the extent the Fund deals with a limited number of counterparties, it will be more susceptible to the credit risks associated with those counterparties. The Fund is neither restricted from dealing with any particular counterparty nor from concentrating any or all of its transactions with one counterparty. The ability of the Fund to transact business with any one or number of counterparties and the absence of a regulated market to facilitate settlement may increase the potential for losses by the Fund.

● Credit Risk. Credit risk refers to the possibility that the issuer of the security or a counterparty in respect of a derivative instrument will not be able to satisfy its payment obligations to the Fund when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. Securities rated in the four highest categories by the rating agencies are considered investment grade but they may also have some speculative characteristics. Investment grade ratings do not guarantee that bonds will not lose value or default. In addition, the credit quality of securities may be lowered if an issuer’s financial condition changes.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. Derivatives include instruments and contracts that are based on, and are valued in relation to, one or more underlying securities, financial benchmarks or indices, such as futures, options, swap agreements and forward contracts. Derivatives typically have economic leverage inherent in their terms. Such leverage will magnify any losses. See “Leverage/Volatility Risk” below. The primary types of derivatives in which the Fund invests in are swap agreements, futures contracts and forward contracts. Futures contracts, forward contracts and swap agreements can be highly volatile, illiquid and difficult to value, and changes in the value of such instruments held directly or indirectly by the Fund may not correlate with the underlying instrument or reference assets, or the Fund’s other investments. Although the value of futures contracts, forward contracts and swap agreements depend largely upon price movements in the underlying instrument or reference asset, there are additional risks associated with futures contracts, forward contracts and swap agreements that are possibly greater than the risks associated with investing directly in the underlying instruments or reference assets, including illiquidity risk, leveraging risk and counterparty credit risk. A small position in futures contracts, forward contracts or swap agreements could have a potentially large impact on the Fund’s performance. Trading restrictions or limitations may be imposed by an exchange, and government regulations may restrict trading in swap agreements, futures contracts and options and forward contracts.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Equity Securities Risk. The Fund may invest in, or have exposure to, equity securities. Equity securities tend to be more volatile than other investment choices, such as debt and money market instruments. The value of your investment may decrease in response to overall stock market movements or the value of individual securities.

● Fixed Income Risk. Fixed income securities, such as U.S. Treasuries, or derivatives based on fixed income securities, are subject to credit risk and interest rate risk. Credit risk, as described more fully above, refers to the possibility that the issuer of a debt security will be unable to make interest payments or repay principal when it becomes due. Interest rate risk refers to fluctuations in the value of a debt security resulting from changes in the general level of interest rates. Prices of fixed income securities tend to move inversely with changes in interest rates. Typically, a rise in rates will adversely affect fixed income security prices and, accordingly, the Fund’s returns and share price. In addition, the Fund may be subject to “call” risk, which is the risk that during a period of falling interest rates the issuer may redeem a security by repaying it early (which may reduce the Fund’s income if the proceeds are reinvested at lower interest rates), and “extension” risk, which occurs during a rising interest rate environment because certain obligations will be paid off by an issuer more slowly than anticipated (causing the value of those securities held by the Fund to fall).

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in, or have exposure to, securities of foreign issuers either directly or depositary receipts. Trading on foreign exchanges is subject to the risks presented by exchange controls, expropriation, increased tax burdens and exposure to local economic declines and political instability. Depositary receipts may be available through “sponsored” or “unsponsored” facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes (“P-notes”) are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk. Some foreign derivative markets are so-called principals’ markets in which performance is the responsibility only of the individual counterparty with whom the trader has entered into a commodity interest transaction and not of the exchange or clearing corporation.

● Futures and Forward Contracts and Related Risks. The successful use of forward and futures contracts draws upon an investment adviser’s skill and experience with respect to such instruments and are subject to special risk considerations. The primary risks associated with the use of futures contracts are (a) the imperfect correlation between the change in market value of instruments held by the Fund and the price of the forward or futures contract; (b) possible lack of a liquid secondary market, and possible regulatory position limits and restrictions, for a forward or futures contract and the resulting inability to close a forward or futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the possibility that the counterparty will default in the performance of its obligations; and (e) if the Fund has insufficient cash, it may have to sell securities from its portfolio to meet daily variation margin requirements, and the Fund may have to sell securities at a time when it may be disadvantageous to do so. The use of futures contracts, forward contracts and derivative instruments will have the economic effect of financial leverage. Financial leverage magnifies exposure to the swings in prices of an asset class underlying an investment and results in increased volatility, which means the Fund will have the potential for greater losses than if the Fund did not employ leverage in its investment activity. Leveraging tends to magnify, sometimes significantly, the effect of any increase or decrease in the Fund’s exposure to an asset class and may cause the value of the Fund’s securities or related derivatives instruments to be volatile. Exposure to the commodities markets (including financial futures markets) may subject the Fund to greater volatility than investments in traditional securities.

● Government Agency Risk. Direct obligations of the U.S. Government such as Treasury bills, notes and bonds are supported by its full faith and credit. Indirect obligations issued by Federal agencies and government-sponsored entities generally are not backed by the full faith and credit of the U.S. Treasury. Accordingly, while U.S. Government agencies and instrumentalities may be chartered or sponsored by Acts of Congress, their securities are neither issued nor guaranteed by the U.S. Treasury. Some of these indirect obligations may be supported by the right of the issuer to borrow from the Treasury; others are supported by the discretionary authority of the U.S. Government to purchase the agency’s obligations; still others are supported only by the credit of the instrumentality.

● Government Intervention and Regulatory Changes. The Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”) (which was passed into law in July 2010) significantly expanded the rulemaking, supervisory and enforcement authority of federal bank, securities and commodities regulators. There can be no assurance that future regulatory actions including, but not limited to, those authorized by the Dodd-Frank Act will not adversely affect the Fund. Major changes resulting from legislative or regulatory actions could materially affect the profitability of the Fund or the value of investments made by the Fund or force the Fund to revise its investment strategy or divest certain of its investments. Any of these developments could expose the Fund to additional costs, taxes, liabilities, enforcement actions and reputational risk.

In addition, the SEC has proposed new regulations regarding mutual funds’ use of derivatives and leverage. These proposed rules, if adopted in substantially the same form as proposed, could have a substantial effect on the ability of the Fund to implement fully its investment strategy as described herein, which may limit the Fund’s ability to achieve its objective.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● Interest Rate Risk. Interest rate risk is the risk that prices of fixed income securities generally increase when interest rates decline and decrease when interest rates increase. The Fund may lose money if short term or long term interest rates rise sharply or otherwise change in a manner not anticipated by a Co-Adviser. Securities with longer maturities tend to be more sensitive to changes in interest rates causing them to be more volatile than securities with shorter maturities. Securities with shorter maturities tend to provide lower returns and be less volatile than securities with longer maturities. There will likely be less governmental action in the near future to maintain low interest rates. The negative effect on fixed income securities from the resulting rate increases for that and other reasons could be swift and significant.

● Investment Company and Exchange-Traded Fund Risk. Investing in other investment companies, including exchange-traded funds (“ETFs”), may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. The risk of owning an investment company or ETF generally reflects the risks of owning the underlying investments the investment company or ETF holds. The Fund may incur brokerage fees in connection with its purchase of ETF shares. Certain ETFs or closed-end funds traded on exchanges may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Co-Advisers cannot guarantee continued access to IPOs.

● Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium-capitalization stocks.

● Leverage/Volatility Risk. Although the Fund will not borrow funds for trading, the Fund should be considered highly leveraged and is suitable only for investors with high tolerance for investment risk. Leverage embedded in the various derivative instruments traded may result in the Fund holding positions whose face or notional value may be many times the Fund’s net asset value (“NAV”). For example, the amount of margin funds necessary to be deposited in order to enter into a futures, forward or option contract position is typically from 2% to 10% of the total face or notional value of the contract, and even a small movement in the price of a commodity can cause a correspondingly large profit or loss. Losses incurred on leveraged investments increase in direct proportion to the degree of leverage employed. Furthermore, derivative instruments and futures contracts are highly volatile and are subject to occasional rapid and substantial fluctuations. Consequently, you could lose all or substantially all of your investment in the Fund should the Fund’s trading positions suddenly turn unprofitable.

● Market Risk. The Fund’s NAV and investment return will fluctuate based upon changes in the value of its investments. You could lose money on your investment in the Fund, or the Fund could underperform other investments.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● New Fund Risk. The Fund is new with no operating history and there can be no assurance that the Fund will grow to or maintain an economically viable size, in which case the Board may determine to liquidate the Fund.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may “cover” a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Co-Adviser is incorrect in its expectation of price fluctuations.

● OTC Trading Risk. Certain of the derivatives in which the Fund may invest may be traded (and privately negotiated) in the “over-the-counter” or “OTC” market. While the OTC derivatives market is the primary trading venue for many derivatives, it is largely unregulated. The Fund is subject to counterparty credit risk with respect to such derivative contracts.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities, if the borrowing institution breaches its agreement with the Fund.

● Short Sales Risk. The Fund may take a short position in a derivative instrument, such as a future, forward or swap or security. A short position on a derivative instrument or security involves the risk of a theoretically unlimited increase in the value of the underlying instrument. Short sales also involve transaction and other costs that will reduce potential Fund gains and increase potential Fund losses.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

Performance information for the Fund is not included because the Fund did not have one full calendar year of performance prior to the date of this Prospectus. Updated performance information will be available on the Fund’s website at www.boston-partners.com or by calling the Fund toll free at 1-888-261-4073.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

Performance information for the Fund is not included because the Fund did not have one full calendar year of performance prior to the date of this Prospectus.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Institutional Class Prospectus | Boston Partners Global Equity Advantage Fund | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

BPCIX

Management Fees

rr_ManagementFeesOverAssets

1.00%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.88%

^[1]

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.44%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.32%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(1.27%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.05%

One Year

rr_ExpenseExampleYear01

$ 1,071

Three Years

rr_ExpenseExampleYear03

$ 6,024

[1] "Other expenses" are estimated for the current fiscal year.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment advisers, Boston Partners Global Investors, Inc. ("Boston Partners" or a "Co-Adviser") and Campbell & Company Investment Adviser LLC ("Campbell" or a "Co-Adviser"), have contractually agreed to waive all or a portion of their advisory fees and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.05% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Co-Advisers' obligations to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.05%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.05% or the expense cap then in effect, whichever is less, the Co-Advisers are entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Co-Advisers to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Matson Money | Matson Money Fixed Income VI Portfolio

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

MATSON MONEY FIXED INCOME VI PORTFOLIO FMVFX

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Matson Money Fixed Income VI Portfolio (for this section only, the “Portfolio”) seeks total return (consisting of current income and capital appreciation).

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Portfolio. This table does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, overall fees and expenses would be higher.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Portfolio shares are held in a taxable account. These costs, which are not reflected in Total Annual Portfolio Operating Expenses or in the Example, affect the Portfolio’s performance. During the fiscal year ended August 31, 2019, the Portfolio’s portfolio turnover rate was 19% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

19.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. This Example does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, the costs shown below would be higher.

The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Portfolio pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in fixed income securities that the Adviser believes offer the prospect of providing total return, or invest substantially all of their assets in such fixed income securities. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Portfolio’s net assets to be invested in the securities of investment companies, including other investment companies funded by insurance company separate accounts, that invest in the types of securities described in each asset class below, with less than 2% of the net assets invested in cash or money market instruments.

One-Year Fixed Income Asset Class: The underlying investment companies generally will purchase U.S. government obligations, U.S. government agency obligations, dollar-denominated obligations of foreign issuers issued in the U.S., securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the U.S., foreign government and agency obligations, bank obligations, including the obligations of U.S. subsidiaries and branches of foreign banks, corporate obligations, commercial paper, repurchase agreements, and obligations of supranational organizations such as the World Bank, the European Investment Bank and the Inter-American Development Bank. Generally, obligations comprising this asset class will mature within one year from the date of settlement, but substantial investments may be made in obligations maturing within two years from the date of settlement when greater returns are available.

Two-Year Global Fixed Income Asset Class: The underlying investment companies generally will purchase obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, corporate debt obligations, bank obligations, commercial paper, repurchase agreements, and other debt obligations of domestic and foreign issuers with maturities of no more than two years. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the underlying investment adviser(s) will focus investment in the longer-term area, otherwise, the underlying investment companies will focus investment in the shorter-term area of the eligible maturity range. Because many of the investments of the underlying investment companies in this asset class will be denominated in foreign currencies, the underlying investment companies may also enter into foreign currency forward contracts to attempt to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another.

Intermediate Government Fixed Income Asset Class: The underlying investment companies generally will purchase debt obligations of the U.S. government and U.S. government agencies. Generally, investment companies in the asset class will purchase securities with maturities of between five and fifteen years, however such investment companies ordinarily will have an average weighted maturity of between three and ten years. The underlying investment companies may invest a portion of their assets in the obligations of foreign governments. Those obligations at the time of purchase must be either rated in the highest rating category of a nationally recognized statistical rating organization or, in the case of any obligation that is unrated, of comparable quality.

Five-Year Global Fixed Income Asset Class: The underlying investment companies generally will purchase obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, corporate debt obligations, bank obligations, commercial paper, repurchase agreements, obligations of other domestic and foreign issuers, securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the United States, and obligations of supranational organizations. Generally, obligations comprising this asset class have a weighted average maturity not exceeding five years. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the underlying investment adviser(s) will focus investment in the longer-term area, otherwise, the underlying investment companies will focus investment in the shorter-term area of the eligible maturity range. Because many of the investments of the underlying investment companies in this asset class will be denominated in foreign currencies, the underlying investment companies may also enter into foreign currency forward contracts to attempt to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another.

Short-Term Corporate Bond Asset Class: The underlying investment companies generally will track the investment results of the ICE BofAML 1-5 Year US Corporate Index, which measures the performance of investment-grade corporate bonds of both U.S. and non- U.S. issuers that are U.S. dollar denominated and publicly issued in the U.S. domestic market and have a remaining maturity of greater than or equal to one year and less than five years.

Intermediate-Term Corporate Bond Asset Class: The underlying investment companies generally will track the investment results of the ICE BofAML 5-10 Year US Corporate Index, which measures the performance of investment-grade corporate bonds of both U.S. and non-U.S. issuers that are U.S. dollar denominated and publicly issued in the U.S. domestic market and have a remaining maturity of greater than or equal to five years and less than ten years.

Inflation Protected Securities Asset Class: The underlying investment companies generally will track the investment results of the Bloomberg Barclays U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L), which measures the performance of the inflation-protected public obligations of the U.S. Treasury, commonly known as “TIPS.” TIPS are securities issued by the U.S. Treasury that are designed to provide inflation protection to investors. TIPS are income-generating instruments whose interest and principal payments are adjusted for inflation - a sustained increase in prices that erodes the purchasing power of money. The inflation adjustment, which is typically applied monthly to the principal of the bond, follows a designated inflation index, the consumer price index (“CPI”), and TIPS’ principal payments are adjusted according to changes in the CPI. A fixed coupon rate is applied to the inflation-adjusted principal so that as inflation rises, both the principal value and the interest payments increase.

The underlying investment companies may also use derivatives, such as futures contracts and options on futures contracts for equity securities and indices, to hedge currency exposure or to adjust market exposure based on actual or expected cash inflows or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, forward currency contracts, options and swaps to help the ETF track its underlying index.

Certain underlying investment companies may concentrate their investments (invest more than 25% of its total assets) in obligations of U.S. and foreign banks and bank holding companies when the yield to maturity on eligible portfolio investments in banking securities as a group generally exceeds the yield to maturity on all other eligible portfolio investments as a group generally for a period of five consecutive days when the New York Stock Exchange (“NYSE”) is open for trading. While the Portfolio will not concentrate its investments in any one industry, the Portfolio may be focused on banking sectors under certain circumstances.

The Portfolio reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Portfolio employs a temporary defensive measure, the Portfolio may not achieve its investment objective. Periodically the Adviser will review the allocations for the Portfolio in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Portfolio in the underlying investment companies without notice to shareholders or the holders of the variable annuity or variable life insurance policies.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Portfolio, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Portfolio, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Fixed income securities in which the Portfolio’s underlying investment companies may invest are subject to certain risks, including: interest rate risk, reinvestment risk, prepayment and extension risk, credit/default risk, and the risks associated with investing in repurchase agreements.

● Interest rate risk involves the risk that prices of fixed income securities will rise and fall in response to interest rate changes.

● Reinvestment risk involves the risk that proceeds from matured investments may be re-invested at lower interest rates.

● Prepayment risk involves the risk that in declining interest rates environments prepayments of principal could increase and require the Portfolio to reinvest proceeds of the prepayments at lower interest rates.

● Extension risk involves the risk that prepayments of principal will decrease when interest rates rise resulting in a longer effective maturity of a security.

● Credit risk is the risk that the issuer of a security may be unable to make interest payments and/or repay principal when due. Credit risk also involves the risk that the credit rating of a security may be lowered.

● Repurchase agreement risk involves the risk that the other party to a repurchase agreement will be unable to complete the transaction and the underlying investment company in which the Portfolio invests may suffer a loss as a result.

● Because the Portfolio owns shares of underlying investment companies that invest in foreign issuers, the Portfolio is subject to risks presented by investments in such issuers. Securities of foreign issuers may be negatively affected by political events, economic conditions, or inefficient, illiquid or unregulated markets in foreign countries. Foreign issuers may be subject to inadequate regulatory or accounting standards.

● Currency risk is the risk that exchange rates for currencies in which securities held by the underlying investment companies in which the Portfolio invests are denominated will fluctuate daily. Forward foreign currency exchange contracts may limit potential gains from a favorable change in value between the U.S. dollar and foreign currencies. Unanticipated changes in currency pricing may result in poorer overall performance for the Portfolio than if it had not engaged in these contracts.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Portfolio could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Portfolio invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in fixed income securities, the NAV of the Portfolio will change with changes in the share prices of the investment companies in which the Portfolio invests.

● Not all obligations of U.S. government agencies and instrumentalities are backed by the full faith and credit of the U.S. Treasury. Some are backed only by the credit of the issuing agency or instrumentality. Accordingly, there may be some risk of default by the issuer in such cases.

● There is a risk that the Portfolio, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Portfolio will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● Banks are very sensitive to changes in money market and general economic conditions. Adverse general economic conditions can cause financial difficulties for a bank’s borrowers and the borrowers’ failure to repay their loans can adversely affect the bank’s financial situation. Banks are subject to extensive regulation and decisions by regulators may limit the loans banks make and the interest rates and fees they charge, which could reduce bank profitability.

● Inflation protected securities, such as TIPS, generally will fluctuate in response to changes in real interest rates, generally decreasing when real interest rates rise and increasing when real interest rates fall. In addition, interest payments on inflation-protected securities will generally vary up or down along with the rate of inflation. Real interest rates are generally measured as a nominal interest less an inflation rate. As such, investors should be aware that an investment in TIPS over a particular timeframe may decrease in value even in an inflationary environment. There can be no assurance that the inflation index used will accurately measure the real rate of inflation in the prices of goods and services. Because of their inflation adjustment feature, inflation-protected bonds typically have lower yields than conventional fixed-rate bonds.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Portfolio may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Cyber security risk is the risk of an unauthorized breach and access to Portfolio assets, Portfolio or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Portfolio, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Portfolio investors from purchasing, redeeming or exchanging shares or receiving distributions. The Portfolio and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Portfolio or its service providers may adversely impact and cause financial losses to the Portfolio or its shareholders.

More information about the Portfolio’s investments and risks is contained under the section entitled “More About Each Portfolio’s Investments and Risks.”

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The chart below illustrates the performance of the Portfolio. The information shows you how the Portfolio’s performance has varied year by year and provides some indication of the risks of investing in the Portfolio. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information shows you how the Portfolio's performance has varied year by year and provides some indication of the risks of investing in the Portfolio.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

(866) 780-0357 Ext. 3863

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.matsonmoney.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 1.89% (quarter ended March 31, 2019)

Worst Quarter: -1.33% (quarter ended December 31, 2016)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns of the Portfolio before and after taxes for the past calendar year, the past five calendar years, and since inception to the average total returns of a broad-based securities market index for the same periods.

Matson Money | Matson Money Fixed Income VI Portfolio | FTSE World Government Bond Index 1-5 Years (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

3.86%

5 Years

rr_AverageAnnualReturnYear05

1.92%

Since Inception

rr_AverageAnnualReturnSinceInception

1.87%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

Matson Money | Matson Money Fixed Income VI Portfolio | Composite Index

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

5.34%

^[1]

5 Years

rr_AverageAnnualReturnYear05

2.04%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

2.03%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

^[1]

Matson Money | Matson Money Fixed Income VI Portfolio | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

FMVFX

Management Fees

rr_ManagementFeesOverAssets

0.50%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.24%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.12%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.86%

One Year

rr_ExpenseExampleYear01

$ 88

Three Years

rr_ExpenseExampleYear03

274

Five Years

rr_ExpenseExampleYear05

476

Ten Years

rr_ExpenseExampleYear10

$ 1,058

Annual Return 2015

rr_AnnualReturn2015

(0.27%)

Annual Return 2016

rr_AnnualReturn2016

0.74%

Annual Return 2017

rr_AnnualReturn2017

0.86%

Annual Return 2018

rr_AnnualReturn2018

0.59%

Annual Return 2019

rr_AnnualReturn2019

4.52%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2019

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.89%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2016

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(1.33%)

1 Year

rr_AverageAnnualReturnYear01

4.52%

5 Years

rr_AverageAnnualReturnYear05

1.28%

Since Inception

rr_AverageAnnualReturnSinceInception

1.12%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

Matson Money | Matson Money Fixed Income VI Portfolio | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

3.82%

^[3]

5 Years

rr_AverageAnnualReturnYear05

0.80%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

0.67%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

^[3]

Matson Money | Matson Money Fixed Income VI Portfolio | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

2.68%

5 Years

rr_AverageAnnualReturnYear05

0.78%

Since Inception

rr_AverageAnnualReturnSinceInception

0.67%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

[1] The Composite Index is comprised of the Three-Month Treasury Bill Index, Bloomberg Barclays Intermediate Government Bond Index, ICE BofAML 1-3 Year US Government/Corporate Index and Bloomberg Barclays U.S. Aggregate Bond Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Portfolio's Investments and Risks."

[2] Acquired Fund Fees and Expenses are indirect fees and expenses that the Portfolio incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Matson Money | Matson Money U.S. Equity VI Portfolio

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

MATSON MONEY U.S. EQUITY VI PORTFOLIO FMVUX

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Matson Money U.S. Equity VI Portfolio (for this section only, the “Portfolio”) seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Portfolio. This table does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, overall fees and expenses would be higher.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Portfolio shares are held in a taxable account. These costs, which are not reflected in Total Annual Portfolio Operating Expenses or in the Example, affect the Portfolio’s performance. During the fiscal year ended August 31, 2019, the Portfolio’s portfolio turnover rate was 17% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

17.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total Annual Portfolio Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds. This Example does not reflect the fees and expenses associated with any variable annuity contract or variable life insurance policy that uses the Portfolio as an investment option. Had those fees and expenses been included, the costs shown below would be higher.

The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Portfolio’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Portfolio pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in equity securities, such as common stocks, preferred stocks or securities convertible into stocks, of U.S. companies, or invest substantially all of their assets in such equity securities. The Portfolio will diversify its investments by investing primarily in investment companies focusing on different segments of the equity markets, including large (“large-cap”), small (“small-cap”) and micro-capitalization (“micro-cap”) equity securities that the Portfolio’s investment adviser (“Adviser”) believes offer the prospect of long-term capital appreciation. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Portfolio’s net assets to be invested in the securities of investment companies, including other investment companies funded by insurance company separate accounts, that invest in the types of securities described in each asset class below, with less than 2% of the net assets invested in cash or money market instruments.

U.S. Large Cap Value Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of large cap companies that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time. Large cap companies are generally considered companies whose market capitalizations are generally in the highest 90% of total market capitalization or companies whose market capitalizations are larger than or equal to the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions.

U.S. Small Cap Value Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of small cap companies that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time. Small cap companies are generally considered companies whose market capitalizations are generally in the lowest 10% of total market capitalization or companies whose market capitalizations are smaller than the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions.

U.S. Large Company Asset Class: The underlying investment companies generally will purchase all of the stocks that comprise the S&P 500^® Index in approximately the proportions they are represented in the S&P 500^® Index. Generally, these are the U.S. stocks with the largest market capitalizations and, as a group, they represent approximately 80% of the total market capitalization of all publicly traded U.S. stocks.

U.S. Small Cap Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of small cap companies primarily based on market capitalization. Small cap companies are generally considered companies whose market capitalizations are generally in the lowest 10% of total market capitalization or companies whose market capitalizations are smaller than the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions. There may be some overlap in the companies in which the U.S. small cap asset class and the U.S. micro cap asset class invest.

U.S. Micro Cap Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of micro cap companies. Micro cap companies are generally considered companies whose market capitalizations are generally in the lowest 5% of total market capitalization or companies whose market capitalizations are smaller than the 1,500th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions. There may be some overlap in the companies in which the U.S. micro cap asset class and the U.S. small cap asset class invest.

The underlying investment companies may use derivatives, such as futures contracts and options on futures contracts for U.S. equity securities and indices, to adjust market exposure based on actual or expected cash inflows to or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, options and swaps to help the ETF track its underlying index.

The Portfolio reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Portfolio employs a temporary defensive measure, the Portfolio may not achieve its investment objective. Periodically the Adviser will review the allocations for the Portfolio in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Portfolio in the underlying investment companies without notice to shareholders or the holders of the variable annuity or variable life insurance policies.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Portfolio, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Portfolio, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Stocks of large cap, small cap or micro cap companies in which the Portfolio’s underlying investment companies invest or in which the Portfolio invests directly may temporarily fall out of favor with investors or may be more volatile than the rest of the U.S. market as a whole.

● The smaller the capitalization of a company, generally the less liquid its stock and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records and are more likely to fail than companies with larger market capitalizations.

● Although the Portfolio will invest in other investment companies that follow a value oriented strategy, value stocks may perform differently from the market as a whole and such a strategy may cause the Portfolio at times to underperform equity funds that use other investment strategies.

● Companies in which the Portfolio’s underlying investment companies invest may suffer unexpected losses or lower than expected earnings or their securities may become difficult or impossible to sell at the time and for the price that the underlying investment adviser(s) would like.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Portfolio could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Portfolio invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in U.S. equity securities, the NAV of the Portfolio will change with changes in the share prices of the investment companies in which the Portfolio invests.

● There is a risk that large, small or micro capitalization stocks may not perform as well as other asset classes or the U.S. stock market as a whole. In the past, large, small and micro capitalization stocks have gone through cycles of doing better or worse than the stock market in general.

● There is a risk that the Portfolio, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Portfolio will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. the Portfolio may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Portfolio’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Cyber security risk is the risk of an unauthorized breach and access to Portfolio assets, Portfolio or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Portfolio, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Portfolio investors from purchasing, redeeming or exchanging shares or receiving distributions. The Portfolio and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Portfolio or its service providers may adversely impact and cause financial losses to the Portfolio or its shareholders.

More information about the Portfolio’s investments and risks is contained under the section entitled “More About Each Portfolio’s Investments and Risks.”

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Portfolio or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The chart below illustrates the performance of the Portfolio. The information shows you how the Portfolio’s performance has varied year by year and provides some indication of the risks of investing in the Portfolio. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information shows you how the Portfolio's performance has varied year by year and provides some indication of the risks of investing in the Portfolio.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

(866) 780-0357 Ext. 3863

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.matsonmoney.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) does not necessarily indicate how the Portfolio will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 11.66% (quarter ended March 31, 2019)

Worst Quarter: -17.62% (quarter ended December 31, 2018)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The following table compares the average annual total returns of the Portfolio before and after taxes for the past calendar year, the past five calendar years, and since inception to the average total returns of a broad-based securities market index for the same periods.

Matson Money | Matson Money U.S. Equity VI Portfolio | Russell 2500® Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

27.77%

5 Years

rr_AverageAnnualReturnYear05

8.93%

Since Inception

rr_AverageAnnualReturnSinceInception

9.17%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

Matson Money | Matson Money U.S. Equity VI Portfolio | Composite Index

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

26.63%

^[1]

5 Years

rr_AverageAnnualReturnYear05

8.85%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

9.60%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

^[1]

Matson Money | Matson Money U.S. Equity VI Portfolio | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

FMVUX

Management Fees

rr_ManagementFeesOverAssets

0.50%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.26%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.29%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.05%

One Year

rr_ExpenseExampleYear01

$ 107

Three Years

rr_ExpenseExampleYear03

334

Five Years

rr_ExpenseExampleYear05

579

Ten Years

rr_ExpenseExampleYear10

$ 1,281

Annual Return 2015

rr_AnnualReturn2015

(4.30%)

Annual Return 2016

rr_AnnualReturn2016

20.58%

Annual Return 2017

rr_AnnualReturn2017

13.32%

Annual Return 2018

rr_AnnualReturn2018

(12.30%)

Annual Return 2019

rr_AnnualReturn2019

22.69%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2019

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.66%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(17.62%)

1 Year

rr_AverageAnnualReturnYear01

22.69%

5 Years

rr_AverageAnnualReturnYear05

7.07%

Since Inception

rr_AverageAnnualReturnSinceInception

7.30%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

Matson Money | Matson Money U.S. Equity VI Portfolio | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

21.11%

^[3]

5 Years

rr_AverageAnnualReturnYear05

5.73%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

6.14%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

^[3]

Matson Money | Matson Money U.S. Equity VI Portfolio | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

14.53%

5 Years

rr_AverageAnnualReturnYear05

5.36%

Since Inception

rr_AverageAnnualReturnSinceInception

5.61%

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 18, 2014

[1] The Composite Index is comprised of the S&P 500® Index, Russell 1000® Value Index, Russell 2000® Index and Russell 2000® Value Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Portfolio's Investments and Risks."

[2] Acquired Fund Fees and Expenses are indirect fees and expenses that the Portfolio incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Portfolio Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Portfolio and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Portfolio shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Matson Money | Free Market International Equity Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

FREE MARKET INTERNATIONAL EQUITY FUND FMNEX

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Free Market International Equity Fund (for this section only, the “Fund”) seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 4% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

4.00%

Expense Exchange Traded Fund Commissions [Text]

rr_ExpenseExchangeTradedFundCommissions

You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in equity securities, such as common stocks, preferred stocks or securities convertible into stocks, of foreign companies, or invest substantially all of their assets in such equity securities. The Fund will diversify its investments by investing primarily in investment companies that focus on different segments of the foreign equity markets, including emerging markets, with little or no focus on domestic equity markets. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Fund’s net assets to be invested in the securities of investment companies that invest in the types of securities described in each asset class below, with less than 5% of the net assets invested in cash or money market instruments.

International Small Cap Value Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of small companies in foreign countries with developed markets that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios, as well as economic conditions and developments in the issuer’s industry. The criteria used for assessing value are subject to change from time to time. The underlying investment adviser(s) determine the maximum market capitalization of a small company with respect to each country. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Large Cap Value Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of large companies in foreign countries with developed markets that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios, as well as economic conditions and developments in the issuer’s industry. The criteria used for assessing value are subject to change from time to time. The underlying investment adviser(s) determine the minimum market capitalization of a large company with respect to each country or region. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Small Company Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of small companies in foreign countries with developed markets. The underlying investment adviser(s) determine the maximum market capitalization of a small company with respect to each country. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

International Large Cap Asset Class: The underlying investment companies generally will purchase the stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of large companies in foreign countries with developed markets. The underlying investment adviser(s) determine the minimum market capitalization of a large company with respect to each country or region. The threshold will vary by country or region, and the dollar amount will change from time to time due to market conditions.

Emerging Markets Asset Class, Emerging Markets Value Asset Class, and Emerging Markets Small Cap Asset Class (collectively, the “Emerging Markets Asset Classes”): Underlying investment companies comprising each Emerging Markets Asset Class generally will purchase stocks and other equity securities, directly or through sponsored or unsponsored depositary receipts, of companies located in emerging market countries, including frontier markets (emerging market countries in an earlier stage of development). The underlying investment companies investing in securities of the Emerging Markets Asset Class and the Emerging Markets Small Cap Asset Class will generally purchase the equity securities of larger and smaller companies, respectively, within each country. The underlying investment adviser(s) determine company size primarily based on market capitalization. The thresholds will vary by country or region, and the dollar amounts will change from time to time due to market conditions.

The underlying investment companies in the Emerging Markets Value Asset Class generally will purchase emerging market equity securities that are deemed by the underlying investment adviser(s) to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time.

The underlying investment companies may use derivatives, such as futures contracts and options on futures contracts for equity securities and indices, to hedge currency exposure or to adjust market exposure based on actual or expected cash inflows or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, forward currency contracts, options and swaps to help the ETF track its underlying index.

The Fund reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Fund employs a temporary defensive measure, the Fund may not achieve its investment objective. Periodically the Adviser will review the allocations for the Fund in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Fund in the underlying investment companies without notice to shareholders.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● The value of particular foreign equity securities which the Fund’s underlying investment companies may purchase or foreign stock markets on which the securities they may purchase are traded may decline in value.

● Stocks of large cap or small cap foreign companies in which the Fund’s underlying investment companies may invest may temporarily fall out of favor with investors or may be more volatile than particular foreign stock markets or foreign stock markets as a whole.

● The smaller the capitalization of a company, generally the less liquid its stock and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records and are more likely to fail than companies with larger market capitalizations.

● Stocks of large cap or small cap foreign companies in which the Fund’s underlying investment companies may invest may suffer unexpected losses or lower than expected earnings or such securities may become difficult or impossible to sell at the time and for the price the underlying investment advisers would like.

● Because the Fund owns shares of underlying investment companies that invest in foreign issuers, the Fund is subject to risks presented by investments in such issuers. Securities of foreign issuers may be negatively affected by political events, economic conditions, or inefficient, illiquid or unregulated markets in foreign countries. Foreign issuers may be subject to inadequate regulatory or accounting standards.

● Investments in emerging market securities by underlying investment companies in which the Fund invests are subject to higher risks than those in developed market countries because there is greater uncertainty in less established markets and economics. The foregoing risks may be greater in frontier markets, which are among the smallest and least mature investment markets.

● Currency risk is the risk that exchange rates for currencies in which securities held by the underlying investment companies in which the Fund invests are denominated will fluctuate daily. In general, the underlying investment companies do not hedge currency risk. As a result, if currencies in which foreign holdings are denominated depreciate against the U.S. Dollar, the value of your investment in the Fund may be adversely affected.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Fund could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Fund invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in equity securities of foreign companies, the NAV of the Fund will change with changes in the share prices of the investment companies in which the Fund invests.

● There is a risk that the Fund, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Fund will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

More information about the Fund’s investments and risks is contained under the section entitled “More About Each Fund’s Investments and Risks.”

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The chart below illustrates the long-term performance of the Fund. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

Performance Information Illustrates Variability of Returns [Text]

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The information shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

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(866) 780-0357 Ext. 3863

Performance Availability Website Address [Text]

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www.matsonmoney.com

Performance Past Does Not Indicate Future [Text]

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Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

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TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 17.69% (quarter ended September 30, 2010)

Worst Quarter: -22.38% (quarter ended September 30, 2011)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns of the Fund before and after taxes for the past calendar year, the past five calendar years and past ten calendar years to the average total returns of a broad-based securities market index for the same periods.

Matson Money | Free Market International Equity Fund | MSCI World (excluding U.S.) Index (reflects no deduction expenses or taxes)

Prospectus [Line Items]

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1 Year

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22.49%

5 Years

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5.42%

10 Years

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5.32%

Matson Money | Free Market International Equity Fund | Composite Index

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

21.10%

^[1]

5 Years

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6.33%

^[1]

10 Years

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5.77%

^[1]

Matson Money | Free Market International Equity Fund | Institutional Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

FMNEX

Management Fees

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0.49%

Distribution and/or Service (12b-1) Fees

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none

Other Expenses

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0.09%

Acquired fund fees and expenses

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0.43%

^[2]

Total Annual Fund Operating Expenses

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1.01%

One Year

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$ 103

Three Years

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322

Five Years

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558

Ten Years

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$ 1,236

Annual Return 2010

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15.95%

Annual Return 2011

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(17.90%)

Annual Return 2012

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19.25%

Annual Return 2013

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21.80%

Annual Return 2014

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(5.52%)

Annual Return 2015

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(2.92%)

Annual Return 2016

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8.10%

Annual Return 2017

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27.74%

Annual Return 2018

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(19.65%)

Annual Return 2019

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17.71%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Sep. 30, 2010

Highest Quarterly Return

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17.69%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Sep. 30, 2011

Lowest Quarterly Return

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(22.38%)

1 Year

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17.71%

5 Years

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4.86%

10 Years

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5.17%

Matson Money | Free Market International Equity Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

17.12%

^[3]

5 Years

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4.00%

^[3]

10 Years

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4.42%

^[3]

Matson Money | Free Market International Equity Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

11.09%

5 Years

rr_AverageAnnualReturnYear05

3.66%

10 Years

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4.04%

[1] The Composite Index is comprised of the MSCI EAFE Index, MSCI EAFE Value Index, MSCI EAFE Small Cap Index, and MSCI Emerging Markets Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Fund's Investments and Risks."

[2] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Total

Institutional Class Prospectus | Boston Partners Emerging Markets Long/Short Fund

SUMMARY SECTION — BOSTON PARTNERS EMERGING MARKETS LONG/SHORT FUND

Investment Objective

The Fund seeks long-term growth of capital.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners Emerging Markets Long/Short Fund Institutional Class
Management Fees	1.50%	[1]
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.59%
Dividend expense on short sales	none
Interest expense on borrowings	none
Acquired fund fees and expenses	0.06%	[2]
Total Annual Fund Operating Expenses	2.15%
Fee Waivers and/or Expense Reimbursements	(0.65%)	[3]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	1.50%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | Boston Partners Emerging Markets Long/Short Fund | Institutional Class | USD ($)	1,526	6,104	10,947	24,315

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 186% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund will pursue its objective through investing in a non-diversified, multi-strategy long-short portfolio of equity securities and financial investments with equity like characteristics designed to provide exposure to emerging markets. Securities are selected by the Adviser using its "three circles" approach which combines a quantitative screening with a fundamental bottom up selection process. This investment strategy is grounded in the following principles: (1) low valuation stocks outperform high valuation stocks; (2) companies with strong fundamentals, e.g. high and sustainable returns on invested capital, outperform companies with weak fundamentals; and (3) stocks with positive business momentum, e.g. rising earnings estimates, outperform stocks with negative business momentum. With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Adviser examines various factors in determining the value characteristics of issuers, including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals, such as return-on-equity and earnings growth and cash flow.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in the securities of emerging market issuers, related derivative instruments and other investments that are tied economically to emerging market countries. The Adviser considers an emerging market country to include any country that is: 1) generally recognized to be an emerging market country by the international financial community, including the World Bank; 2) classified by the United Nations as a developing country; or 3) included in the MSCI Emerging Markets Index. Due to the unique relationship between China and its separately administered regions, the Adviser includes Hong Kong and Macau as emerging markets, independent of above definitions 1 through 3. The Adviser determines that an investment is tied economically to an emerging market if such investment satisfies one or more of the following conditions: 1) the issuer’s primary trading market is in an emerging market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in emerging markets; 3) the investment is included in an index representative of emerging markets; and 4) the investment is exposed to the economic risks and returns of emerging markets.

In managing the Fund’s portfolio, the Adviser will seek to identify mispriced publicly traded equity securities of emerging market companies including shorting securities that the Adviser believes will underperform and purchasing securities that the Adviser believes will outperform.

The long portion of the portfolio will emphasize low valuation, positive business momentum and high quality securities. The short portfolio will emphasize securities with high valuation risk, high balance sheet risk and signs of slowing sales and earnings momentum.

The Fund’s portfolio is rebalanced regularly to maintain the optimal risk/return trade-off. The Adviser assesses each stock’s changing characteristics relative to its contribution to portfolio risk. The Adviser will sell a stock held long or close out a short position in a stock that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

The equity securities in which the Fund will invest include equity securities issued by large-, mid- and small- or micro-cap companies, as well as exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers").

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by S&P Global, or have a comparable rating by another nationally recognized statistical rating organization (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded. The Fund will primarily invest in fixed income instruments, including high yield fixed income obligations, when the Fund believes that such instruments offer a better risk/reward profile than comparable equity opportunities.

Under normal circumstances, the Adviser expects that the Fund’s long positions will not exceed approximately 50% of the Fund’s net assets with a typical range of 30% to 70% net long.

The Fund’s long and short positions may involve (without limit) equity securities of non-U.S. issuers that are traded in the markets of the United States.

In addition to the short sales discussed above, the Fund may make short sales "against the box," a transaction in which the Fund enters into a short sale of a security which the Fund owns. The proceeds of the short sale will be held by a broker until the settlement date at which time the Fund delivers the security to close the short position. The Fund receives the net proceeds from the short sale. It is currently expected that the majority of the Fund’s short sales will not be against the box.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Fund is the sole shareholder of Boston Partners Emerging Markets Long/Short Offshore Ltd., a wholly-owned subsidiary organized under the laws of the Cayman Islands (the “Subsidiary”). Generally, the Subsidiary invests primarily in futures contracts traded on Indian stock exchanges. The Fund and its Subsidiary comply with the same fundamental investment restrictions on an aggregate basis, to the extent those restrictions are applicable to the investment activities of the Subsidiary. The Fund is the sole shareholder of its Subsidiary and does not expect shares of its Subsidiary to be offered or sold to other investors. An election has been made to cause the Subsidiary to be a disregarded entity for U.S. federal income tax purposes; accordingly, the assets and income of the Subsidiary will be treated for U.S. federal income tax purposes no differently from the other assets and income of the Fund.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund’s investments will be spread over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest in exchange traded funds to the extent permitted by the Investment Company Act of 1940, as amended (“1940 Act”), and applicable SEC orders.

The Fund may participate as a purchaser in initial public offerings of securities (“IPOs”). An IPO is a company’s first offering of stock to the public.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may also seek to increase its income by lending portfolio securities.

The Fund will invest in derivatives, including put and call options, futures, contracts for differences, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes. Contracts for differences offer exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin. The Fund’s investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, contracts for differences, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may not be successful in its strategy of taking long positions in securities the Adviser believes to be undervalued and short positions in securities the Adviser believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make. Investments the Fund makes may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund’s assets could impede portfolio management or the Fund’s ability to meet redemption requests or other current obligations.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling is speculative and also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund’s obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in the value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund’s loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

● Subsidiary Risks. By investing in the Subsidiary, the Fund is indirectly exposed to the risks associated with the Subsidiary’s investments. The derivatives and other investments held by the Subsidiary are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund. The Subsidiary is not registered under the 1940 Act, and, unless otherwise noted in this Prospectus, is not subject to all the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to continue to operate as it does currently and could adversely affect the Fund.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Performance Information

The bar chart and table below illustrate the long-term performance of the Fund. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

The Fund commenced operations as a series of The RBB Fund, Inc. on December 15, 2015, when substantially all of the assets of Boston Partners Emerging Markets Long/Short Equity (the “Prior Account”) transferred to the Fund. The Fund is managed in all material respects in a manner equivalent to the management of the Prior Account. Accordingly, the performance information shown below for periods prior to December 15, 2015 is that of the Prior Account. The Fund’s objectives, policies, guidelines and restrictions are in all material respects equivalent to the Prior Account. The Fund is managed by Joseph F. Feeney, Jr. and Paul Korngiebel, the same Prior Account portfolio managers that managed the Prior Account since its inception in 2015. The Prior Account was not registered under the Investment Company Act of 1940, as amended (“1940 Act”), and thus was not subject to certain investment and operational restrictions that are imposed by the 1940 Act. If the Prior Account had been registered under the 1940 Act, its performance may have been adversely affected. Accordingly, future Fund performance may be different than the Prior Account’s restated past performance. The Prior Account’s performance has been restated to reflect estimated expenses of the Fund. After-tax performance returns are not included for the Prior Account. The Prior Account was not a regulated investment company under Subchapter M of the Internal Revenue Code and therefore did not distribute current or accumulated earnings and profits and was not subject to the diversification and source of income requirements applicable to regulated investment companies.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	9.42% (quarter ended March 31, 2017)
Worst Quarter:	-8.82% (quarter ended December 31, 2018)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund's Institutional Class, including the Prior Account, both before and after taxes for the past calendar year and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Average Annual Total Returns - Institutional Class Prospectus - Boston Partners Emerging Markets Long/Short Fund		1 Year	Since Inception	[1]	Inception Date
Institutional Class		17.46%	4.25%		Mar. 01, 2015
Institutional Class | After Taxes on Distributions	[2]	16.74%	2.83%		Mar. 01, 2015
Institutional Class | After Taxes on Distributions and Sales		10.60%	2.69%		Mar. 01, 2015
MSCI® Emerging Markets Index - Net Return (reflects no deduction for fees, expenses or taxes)	[3]	18.42%	5.01%		Mar. 01, 2015
MSCI® Emerging Markets Index - Gross Return (reflects no deduction for fees, expenses or taxes)	[3]	18.88%	5.41%		Mar. 01, 2015

[1] Prior to October 1, 2019, the management fee was 1.85%.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 1.50% of the average daily net assets attributable to the Fund's Institutional Class shares. Because short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and/or expense reimbursements) are expected to exceed 1.50%. This contractual limitation is in effect until February 28, 2022 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.50% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] The "Since Inception" performance includes performance from the Prior Account beginning on March 1, 2015 until the Fund's commencement of operations on December 15, 2015.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

[3] Effective August 31, 2019, the Fund changed its primary index from the MSCI Emerging Markets Index - Gross Return to the MSCI Emerging Markets Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

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Institutional Class Prospectus | Boston Partners Global Equity Advantage Fund

SUMMARY SECTION - BOSTON PARTNERS GLOBAL EQUITY ADVANTAGE FUND

Investment Objective

The Fund seeks to provide long-term capital appreciation.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners Global Equity Advantage Fund Institutional Class
Management Fees	1.00%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.88%	[1]
Acquired fund fees and expenses	0.44%	[2]
Total Annual Fund Operating Expenses	2.32%
Fee Waivers and/or Expense Reimbursements	(1.27%)	[3]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	1.05%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same (taking into account the contractual expense limitation until its expiration). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years
Institutional Class Prospectus | Boston Partners Global Equity Advantage Fund | Institutional Class | USD ($)	1,071	6,024

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the period from the Fund’s inception on May 29, 2019 through the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 16% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund seeks to achieve its investment objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity- related securities, including exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds (“ETFs”)), real estate investment trusts (“REITs”) and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% - unless market conditions are not deemed favorable by the Fund, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by a Co-Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Fund applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Fund considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer’s inherent value. The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities. The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund also seeks to diversify its overall portfolio by investing, under normal circumstances, up to 20% of its assets in the Campbell Advantage strategy, a systematic trend following program, which is diversified across global futures and forwards markets (types of derivative instruments). The Campbell Advantage strategy is designed to analyze market data to identify trends occurring within and across markets and asset classes globally. By trading four major asset classes (equity index futures, fixed income futures, commodities and foreign exchange), the portfolio composition is diverse and expected to maintain low correlation with equities over time. Additionally, portfolio risk is dynamically managed through a framework intended to maximize the Campbell Advantage strategy’s ability to complement the global long equity exposure in an attempt to limit the Fund’s downside risk during extended periods of high equity market volatility.

The Fund’s investments may include investments in registered and unregistered funds managed by Campbell or an affiliate to obtain exposure to the Campbell Advantage strategy. The Fund will invest in such affiliated funds only in accordance with the applicable restrictions of the 1940 Act, including Section 12(d)(1).

The Fund is “non-diversified” for purposes of the Investment Company Act of 1940, as amended, (the “1940 Act”) which means that the Fund may invest in fewer securities at any one time than a diversified fund. The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund’s Co-Advisers are Boston Partners and Campbell. Boston Partners is primarily responsible for managing the equity portion of the Fund’s portfolio, including equity securities and related derivative contracts. Campbell is primarily responsible for managing the Fund’s exposure to the Campbell Advantage strategy. Campbell is also primarily responsible for determining the allocation of the Fund’s portfolio between equity and other investments. Each Co-Adviser may also from time to time consult and work collaboratively with, or be informed by the decisions of or information from, one or both of the other Co-Advisers in connection with making certain investment decisions in regards to the Fund’s investment strategies and portfolio, in addition to various compliance, operational and administrative matters. While the Co-Advisers may work collaboratively in connection with the management of the Fund’s portfolio as described above, under certain circumstances, such as, for example, when certain personnel at another Co-Adviser are not available, a Co-Adviser may make decisions or otherwise act independently from the other Co-Advisers.

The Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Co-Advisers will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Active Management Risk. The Co-Advisers’ judgments about the attractiveness, value, or potential appreciation of the Fund’s investments may prove to be incorrect. The Fund could underperform in comparison to other funds with a similar benchmark or similar objectives and investment strategies if the Fund’s overall asset allocation, investment selections or strategies fail to produce the intended results.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Counterparty Risk. The derivative contracts entered into by the Fund may be privately negotiated in the over-the-counter market. These contracts also involve exposure to credit risk, since contract performance depends in part on the financial condition of the counterparty. Relying on a counterparty exposes the Fund to the risk that a counterparty will not settle a transaction in accordance with its terms and conditions because of a dispute over the terms of the contract (whether or not bona fide) or because of a credit or liquidity problem, thus causing the Fund to suffer a loss. If a counterparty defaults on its payment obligations to the Fund, this default will cause the value of an investment in the Fund to decrease. In addition, to the extent the Fund deals with a limited number of counterparties, it will be more susceptible to the credit risks associated with those counterparties. The Fund is neither restricted from dealing with any particular counterparty nor from concentrating any or all of its transactions with one counterparty. The ability of the Fund to transact business with any one or number of counterparties and the absence of a regulated market to facilitate settlement may increase the potential for losses by the Fund.

● Credit Risk. Credit risk refers to the possibility that the issuer of the security or a counterparty in respect of a derivative instrument will not be able to satisfy its payment obligations to the Fund when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. Securities rated in the four highest categories by the rating agencies are considered investment grade but they may also have some speculative characteristics. Investment grade ratings do not guarantee that bonds will not lose value or default. In addition, the credit quality of securities may be lowered if an issuer’s financial condition changes.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. Derivatives include instruments and contracts that are based on, and are valued in relation to, one or more underlying securities, financial benchmarks or indices, such as futures, options, swap agreements and forward contracts. Derivatives typically have economic leverage inherent in their terms. Such leverage will magnify any losses. See “Leverage/Volatility Risk” below. The primary types of derivatives in which the Fund invests in are swap agreements, futures contracts and forward contracts. Futures contracts, forward contracts and swap agreements can be highly volatile, illiquid and difficult to value, and changes in the value of such instruments held directly or indirectly by the Fund may not correlate with the underlying instrument or reference assets, or the Fund’s other investments. Although the value of futures contracts, forward contracts and swap agreements depend largely upon price movements in the underlying instrument or reference asset, there are additional risks associated with futures contracts, forward contracts and swap agreements that are possibly greater than the risks associated with investing directly in the underlying instruments or reference assets, including illiquidity risk, leveraging risk and counterparty credit risk. A small position in futures contracts, forward contracts or swap agreements could have a potentially large impact on the Fund’s performance. Trading restrictions or limitations may be imposed by an exchange, and government regulations may restrict trading in swap agreements, futures contracts and options and forward contracts.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Equity Securities Risk. The Fund may invest in, or have exposure to, equity securities. Equity securities tend to be more volatile than other investment choices, such as debt and money market instruments. The value of your investment may decrease in response to overall stock market movements or the value of individual securities.

● Fixed Income Risk. Fixed income securities, such as U.S. Treasuries, or derivatives based on fixed income securities, are subject to credit risk and interest rate risk. Credit risk, as described more fully above, refers to the possibility that the issuer of a debt security will be unable to make interest payments or repay principal when it becomes due. Interest rate risk refers to fluctuations in the value of a debt security resulting from changes in the general level of interest rates. Prices of fixed income securities tend to move inversely with changes in interest rates. Typically, a rise in rates will adversely affect fixed income security prices and, accordingly, the Fund’s returns and share price. In addition, the Fund may be subject to “call” risk, which is the risk that during a period of falling interest rates the issuer may redeem a security by repaying it early (which may reduce the Fund’s income if the proceeds are reinvested at lower interest rates), and “extension” risk, which occurs during a rising interest rate environment because certain obligations will be paid off by an issuer more slowly than anticipated (causing the value of those securities held by the Fund to fall).

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in, or have exposure to, securities of foreign issuers either directly or depositary receipts. Trading on foreign exchanges is subject to the risks presented by exchange controls, expropriation, increased tax burdens and exposure to local economic declines and political instability. Depositary receipts may be available through “sponsored” or “unsponsored” facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes (“P-notes”) are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk. Some foreign derivative markets are so-called principals’ markets in which performance is the responsibility only of the individual counterparty with whom the trader has entered into a commodity interest transaction and not of the exchange or clearing corporation.

● Futures and Forward Contracts and Related Risks. The successful use of forward and futures contracts draws upon an investment adviser’s skill and experience with respect to such instruments and are subject to special risk considerations. The primary risks associated with the use of futures contracts are (a) the imperfect correlation between the change in market value of instruments held by the Fund and the price of the forward or futures contract; (b) possible lack of a liquid secondary market, and possible regulatory position limits and restrictions, for a forward or futures contract and the resulting inability to close a forward or futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the possibility that the counterparty will default in the performance of its obligations; and (e) if the Fund has insufficient cash, it may have to sell securities from its portfolio to meet daily variation margin requirements, and the Fund may have to sell securities at a time when it may be disadvantageous to do so. The use of futures contracts, forward contracts and derivative instruments will have the economic effect of financial leverage. Financial leverage magnifies exposure to the swings in prices of an asset class underlying an investment and results in increased volatility, which means the Fund will have the potential for greater losses than if the Fund did not employ leverage in its investment activity. Leveraging tends to magnify, sometimes significantly, the effect of any increase or decrease in the Fund’s exposure to an asset class and may cause the value of the Fund’s securities or related derivatives instruments to be volatile. Exposure to the commodities markets (including financial futures markets) may subject the Fund to greater volatility than investments in traditional securities.

● Government Agency Risk. Direct obligations of the U.S. Government such as Treasury bills, notes and bonds are supported by its full faith and credit. Indirect obligations issued by Federal agencies and government-sponsored entities generally are not backed by the full faith and credit of the U.S. Treasury. Accordingly, while U.S. Government agencies and instrumentalities may be chartered or sponsored by Acts of Congress, their securities are neither issued nor guaranteed by the U.S. Treasury. Some of these indirect obligations may be supported by the right of the issuer to borrow from the Treasury; others are supported by the discretionary authority of the U.S. Government to purchase the agency’s obligations; still others are supported only by the credit of the instrumentality.

● Government Intervention and Regulatory Changes. The Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”) (which was passed into law in July 2010) significantly expanded the rulemaking, supervisory and enforcement authority of federal bank, securities and commodities regulators. There can be no assurance that future regulatory actions including, but not limited to, those authorized by the Dodd-Frank Act will not adversely affect the Fund. Major changes resulting from legislative or regulatory actions could materially affect the profitability of the Fund or the value of investments made by the Fund or force the Fund to revise its investment strategy or divest certain of its investments. Any of these developments could expose the Fund to additional costs, taxes, liabilities, enforcement actions and reputational risk.

In addition, the SEC has proposed new regulations regarding mutual funds’ use of derivatives and leverage. These proposed rules, if adopted in substantially the same form as proposed, could have a substantial effect on the ability of the Fund to implement fully its investment strategy as described herein, which may limit the Fund’s ability to achieve its objective.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● Interest Rate Risk. Interest rate risk is the risk that prices of fixed income securities generally increase when interest rates decline and decrease when interest rates increase. The Fund may lose money if short term or long term interest rates rise sharply or otherwise change in a manner not anticipated by a Co-Adviser. Securities with longer maturities tend to be more sensitive to changes in interest rates causing them to be more volatile than securities with shorter maturities. Securities with shorter maturities tend to provide lower returns and be less volatile than securities with longer maturities. There will likely be less governmental action in the near future to maintain low interest rates. The negative effect on fixed income securities from the resulting rate increases for that and other reasons could be swift and significant.

● Investment Company and Exchange-Traded Fund Risk. Investing in other investment companies, including exchange-traded funds (“ETFs”), may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. The risk of owning an investment company or ETF generally reflects the risks of owning the underlying investments the investment company or ETF holds. The Fund may incur brokerage fees in connection with its purchase of ETF shares. Certain ETFs or closed-end funds traded on exchanges may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Co-Advisers cannot guarantee continued access to IPOs.

● Large-Cap Companies Risk. The stocks of large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus solely on small- or medium-capitalization stocks.

● Leverage/Volatility Risk. Although the Fund will not borrow funds for trading, the Fund should be considered highly leveraged and is suitable only for investors with high tolerance for investment risk. Leverage embedded in the various derivative instruments traded may result in the Fund holding positions whose face or notional value may be many times the Fund’s net asset value (“NAV”). For example, the amount of margin funds necessary to be deposited in order to enter into a futures, forward or option contract position is typically from 2% to 10% of the total face or notional value of the contract, and even a small movement in the price of a commodity can cause a correspondingly large profit or loss. Losses incurred on leveraged investments increase in direct proportion to the degree of leverage employed. Furthermore, derivative instruments and futures contracts are highly volatile and are subject to occasional rapid and substantial fluctuations. Consequently, you could lose all or substantially all of your investment in the Fund should the Fund’s trading positions suddenly turn unprofitable.

● Market Risk. The Fund’s NAV and investment return will fluctuate based upon changes in the value of its investments. You could lose money on your investment in the Fund, or the Fund could underperform other investments.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● New Fund Risk. The Fund is new with no operating history and there can be no assurance that the Fund will grow to or maintain an economically viable size, in which case the Board may determine to liquidate the Fund.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may “cover” a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Co-Adviser is incorrect in its expectation of price fluctuations.

● OTC Trading Risk. Certain of the derivatives in which the Fund may invest may be traded (and privately negotiated) in the “over-the-counter” or “OTC” market. While the OTC derivatives market is the primary trading venue for many derivatives, it is largely unregulated. The Fund is subject to counterparty credit risk with respect to such derivative contracts.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities, if the borrowing institution breaches its agreement with the Fund.

● Short Sales Risk. The Fund may take a short position in a derivative instrument, such as a future, forward or swap or security. A short position on a derivative instrument or security involves the risk of a theoretically unlimited increase in the value of the underlying instrument. Short sales also involve transaction and other costs that will reduce potential Fund gains and increase potential Fund losses.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

Performance Information

Performance information for the Fund is not included because the Fund did not have one full calendar year of performance prior to the date of this Prospectus. Updated performance information will be available on the Fund’s website at www.boston-partners.com or by calling the Fund toll free at 1-888-261-4073.

[1] "Other expenses" are estimated for the current fiscal year.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment advisers, Boston Partners Global Investors, Inc. ("Boston Partners" or a "Co-Adviser") and Campbell & Company Investment Adviser LLC ("Campbell" or a "Co-Adviser"), have contractually agreed to waive all or a portion of their advisory fees and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.05% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Co-Advisers' obligations to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.05%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.05% or the expense cap then in effect, whichever is less, the Co-Advisers are entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Co-Advisers to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

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Investor Class Prospectus | Boston Partners All-Cap Value Fund

SUMMARY SECTION — BOSTON PARTNERS ALL-CAP VALUE FUND

Investment Objective

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Investor Class Prospectus Boston Partners All-Cap Value Fund Investor Class
Management Fees	0.70%
Distribution and/or Service (12b-1) Fees	0.25%
Other Expenses	0.12%
Acquired fund fees and expenses	0.01%	[1]
Total Annual Fund Operating Expenses	1.08%
Fee Waivers and/or Expense Reimbursements	(0.03%)	[2]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	1.05%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Investor Class Prospectus | Boston Partners All-Cap Value Fund | Investor Class | USD ($)	107	287	483	1,048

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 33% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers across the capitalization spectrum and identified by the Adviser as having value characteristics.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals, such as return on equity and earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may also invest up to 20% of its total assets in non U.S. dollar denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

The Fund may invest up to 10% of its net assets in securities that can be converted into common stock, such as certain debt securities and preferred stock.

The Fund may hedge overall portfolio exposure up to 40% of its net assets through the purchase and sale of index and individual put and call options.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may “cover” a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

● Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners All-Cap Value Fund’s Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	13.26% (quarter ended December 31, 2011)
Worst Quarter:	-17.62% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Investor Class Prospectus - Boston Partners All-Cap Value Fund		1 Year	5 Years	10 Years
Investor Class		27.54%	8.75%	11.78%
Investor Class | After Taxes on Distributions	[1]	26.84%	7.61%	10.75%
Investor Class | After Taxes on Distributions and Sales		16.79%	6.71%	9.56%
Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)		26.26%	8.20%	11.71%

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.05% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.05%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.05% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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RBB FUND, INC.

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Feb. 28, 2020

Matson Money | Free Market U.S. Equity Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

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FREE MARKET U.S. EQUITY FUND FMUEX

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The Free Market U.S. Equity Fund (for this section only, the “Fund”) seeks long-term capital appreciation.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 7% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

7.00%

Expense Exchange Traded Fund Commissions [Text]

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You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs and returns might be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its investment objective by investing under normal circumstances at least 80% of its net assets, including any borrowings for investment purposes, in shares of registered, open-end investment companies and exchange-traded funds (“ETFs”) (collectively, “investment companies”) that have either adopted policies to invest at least 80% of their assets in equity securities, such as common stocks, preferred stocks or securities convertible into stocks, of U.S. companies, or invest substantially all of their assets in such equity securities. The Fund will diversify its investments by investing primarily in investment companies focusing on different segments of the equity markets, including large (“large-cap”), small (“small-cap”) and micro-capitalization (“micro-cap”) equity securities that the Fund’s investment adviser (“Adviser”) believes offer the prospect of long-term capital appreciation. The purchase of shares of investment companies may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses.

Under normal market conditions, the Adviser expects substantially all of the Fund’s net assets to be invested in the securities of investment companies that invest in the types of securities described in each asset class below, with less than 2% of the net assets invested in cash or money market instruments.

U.S. Large Cap Value Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of large cap companies that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time. Large cap companies are generally considered companies whose market capitalizations are generally in the highest 90% of total market capitalization or companies whose market capitalizations are larger than or equal to the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions.

U.S. Small Cap Value Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of small cap companies that the underlying investment adviser(s) determine to be value stocks at the time of purchase. An issuer’s securities are considered value stocks primarily because they have a low price in relation to their book value. In assessing value, the underlying investment adviser(s) may consider additional factors such as price to cash flow or price to earnings ratios. The criteria used for assessing value are subject to change from time to time. Small cap companies are generally considered companies whose market capitalizations are generally in the lowest 10% of total market capitalization or companies whose market capitalizations are smaller than the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions.

U.S. Large Company Asset Class: The underlying investment companies generally will purchase all of the stocks that comprise the S&P 500^® Index in approximately the proportions they are represented in the S&P 500^® Index. Generally, these are the U.S. stocks with the largest market capitalizations and, as a group, they represent approximately 80% of the total market capitalization of all publicly traded U.S. stocks.

U.S. Small Cap Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of small cap companies primarily based on market capitalization. Small cap companies are generally considered companies whose market capitalizations are generally in the lowest 10% of total market capitalization or companies whose market capitalizations are smaller than the 1,000th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions. There may be some overlap in the companies in which the U.S. small cap asset class and the U.S. micro cap asset class invest.

U.S. Micro Cap Asset Class: The underlying investment companies generally will purchase common stocks and other equity securities of micro cap companies. Micro cap companies are generally considered companies whose market capitalizations are generally in the lowest 5% of total market capitalization or companies whose market capitalizations are smaller than the 1,500th largest U.S. company, whichever results in the higher market capitalization break. Total market capitalization is based on the market capitalization of U.S. operating companies listed on a securities exchange in the United States that is deemed appropriate by the underlying investment adviser(s). The dollar amount will change from time to time due to market conditions. There may be some overlap in the companies in which the U.S. micro cap asset class and the U.S. small cap asset class invest.

The underlying investment companies may use derivatives, such as futures contracts and options on futures contracts for U.S. equity securities and indices, to adjust market exposure based on actual or expected cash inflows to or outflows from the underlying investment company. Underlying index-based ETFs may use derivatives, including futures contracts, options on futures contracts, options and swaps to help the ETF track its underlying index.

The Fund reserves the right to hold up to 100% of its assets as a temporary defensive measure in cash and money market instruments such as U.S. government securities, bank obligations and commercial paper. To the extent the Fund employs a temporary defensive measure, the Fund may not achieve its investment objective. Periodically the Adviser will review the allocations for the Fund in each underlying investment company and may add or remove underlying investment companies and/or change the investment allocation percentages of the Fund in the underlying investment companies without notice to shareholders.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Stocks of large cap, small cap or micro cap companies in which the Fund’s underlying investment companies invest or in which the Fund invests directly may temporarily fall out of favor with investors or may be more volatile than the rest of the U.S. market as a whole.

● The smaller the capitalization of a company, generally the less liquid its stock and the more volatile its price. Companies with smaller market capitalizations also tend to have unproven track records and are more likely to fail than companies with larger market capitalizations.

● Although the Fund will invest in other investment companies that follow a value oriented strategy, value stocks may perform differently from the market as a whole and such a strategy may cause the Fund at times to underperform equity funds that use other investment strategies.

● Companies in which the Fund’s underlying investment companies invest may suffer unexpected losses or lower than expected earnings or their securities may become difficult or impossible to sell at the time and for the price that the underlying investment adviser(s) would like.

● The Adviser’s judgment about the attractiveness or potential appreciation of a particular underlying investment company security could prove to be wrong or the Fund could miss out on an investment opportunity because the assets necessary to take advantage of such opportunity are tied up in less advantageous investments.

● Because under normal circumstances the Fund invests at least 80% of its net assets in shares of registered investment companies that emphasize investments in U.S. equity securities, the NAV of the Fund will change with changes in the share prices of the investment companies in which the Fund invests.

● There is a risk that large, small or micro capitalization stocks may not perform as well as other asset classes or the U.S. stock market as a whole. In the past, large, small and micro capitalization stocks have gone through cycles of doing better or worse than the stock market in general.

● There is a risk that the Fund, which is passively managed, may not perform as well as funds with more active methods of investment management, such as selecting securities based on economic, financial, and market analysis.

● The derivative instruments in which the underlying investment companies may invest are subject to a number of risks including liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate or index, and it is possible to lose more than the principal amount invested.

● The performance of the Fund will depend on how successfully the investment adviser(s) to the underlying investment companies pursue their investment strategies.

● ETFs are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

More information about the Fund’s investments and risks is contained under the section entitled “More About Each Fund’s Investments and Risks.”

Risk Lose Money [Text]

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You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The chart below illustrates the long-term performance of the Fund. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated information is available at www.matsonmoney.com or by calling (866) 780-0357 Ext. 3863.

Performance Information Illustrates Variability of Returns [Text]

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The information shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

(866) 780-0357 Ext. 3863

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.matsonmoney.com

Performance Past Does Not Indicate Future [Text]

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Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

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TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the period reflected in the chart above)

Best Quarter: 15.21% (quarter ended December 31, 2010)

Worst Quarter: -21.03% (quarter ended September 30, 2011)

Performance Table Heading

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Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns of the Fund before and after taxes for the past calendar year, the past five calendar years, and past ten calendar years to the average total returns of a broad-based securities market index for the same periods.

Matson Money | Free Market U.S. Equity Fund | Russell 2500® Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

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1 Year

rr_AverageAnnualReturnYear01

27.77%

5 Years

rr_AverageAnnualReturnYear05

8.93%

10 Years

rr_AverageAnnualReturnYear10

12.58%

Matson Money | Free Market U.S. Equity Fund | Composite Index

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

26.63%

^[1]

5 Years

rr_AverageAnnualReturnYear05

8.85%

^[1]

10 Years

rr_AverageAnnualReturnYear10

11.96%

^[1]

Matson Money | Free Market U.S. Equity Fund | Institutional Class

Prospectus [Line Items]

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Trading Symbol

dei_TradingSymbol

FMUEX

Management Fees

rr_ManagementFeesOverAssets

0.49%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

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0.06%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.30%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.85%

One Year

rr_ExpenseExampleYear01

$ 87

Three Years

rr_ExpenseExampleYear03

272

Five Years

rr_ExpenseExampleYear05

473

Ten Years

rr_ExpenseExampleYear10

$ 1,053

Annual Return 2010

rr_AnnualReturn2010

24.54%

Annual Return 2011

rr_AnnualReturn2011

(4.09%)

Annual Return 2012

rr_AnnualReturn2012

19.22%

Annual Return 2013

rr_AnnualReturn2013

39.69%

Annual Return 2014

rr_AnnualReturn2014

6.21%

Annual Return 2015

rr_AnnualReturn2015

(4.27%)

Annual Return 2016

rr_AnnualReturn2016

21.22%

Annual Return 2017

rr_AnnualReturn2017

13.44%

Annual Return 2018

rr_AnnualReturn2018

(11.87%)

Annual Return 2019

rr_AnnualReturn2019

22.47%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

15.21%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(21.03%)

1 Year

rr_AverageAnnualReturnYear01

22.47%

5 Years

rr_AverageAnnualReturnYear05

7.28%

10 Years

rr_AverageAnnualReturnYear10

11.62%

Matson Money | Free Market U.S. Equity Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

20.93%

^[3]

5 Years

rr_AverageAnnualReturnYear05

5.87%

^[3]

10 Years

rr_AverageAnnualReturnYear10

10.63%

^[3]

Matson Money | Free Market U.S. Equity Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

14.40%

5 Years

rr_AverageAnnualReturnYear05

5.49%

10 Years

rr_AverageAnnualReturnYear10

9.51%

[1] The Composite Index is comprised of the S&P 500® Index, Russell 1000® Value Index, Russell 2000® Index and Russell 2000® Value Index, each weighted 25%, 25%, 25% and 25%, respectively. Additional information about the Composite Index can be found under the section entitled "More About Each Fund's Investments and Risks."

[2] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses. Acquired Fund Fees and Expenses have been restated for the current fiscal year.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns will depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Investor Class Prospectus | Boston Partners Global Equity Fund

Prospectus [Line Items]

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Risk/Return [Heading]

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SUMMARY SECTION — BOSTON PARTNERS GLOBAL EQUITY FUND

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term capital growth.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund’s Institutional Class was 97% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

97.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds (“ETFs”)) and real estate investment trusts (“REITs”), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by the Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Adviser applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Adviser considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer’s inherent value.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”).An IPO is a company’s first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds (“ETFs”) are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees in addition to the Fund’s own expenses.Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through “sponsored” or “unsponsored” facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes (“P-notes”) are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may “cover” a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage fund and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law, or (ii) maintain their exemptions from registrations under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. Redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

As of the date of this Prospectus, the Boston Partners Global Equity Fund’s Investor Class has not yet commenced operations. The bar chart and table below illustrate the performance of the Fund’s Institutional Class, which is offered in a separate Prospectus. Had the Investor Class been operational during the periods in the chart and table below, it would have had substantially similar annual returns as the Institutional Class because the Investor Class is invested in the same portfolio of securities. Annual returns would differ only to the extent that the Investor Class and Institutional Class do not have the same expenses. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risk of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year by year and provides some indication of the risk of investing in the Fund.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

As of the date of this Prospectus, the Boston Partners Global Equity Fund's Investor Class has not yet commenced operations.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	11.70% (quarter ended March 31, 2012)
Worst Quarter:	-14.86% (quarter ended December 31, 2018)

Bar Chart, Returns for Class Not Offered in Prospectus [Text]

rr_BarChartReturnsForClassNotOfferedInProspectus

The bar chart and table below illustrate the performance of the Fund's Institutional Class, which is offered in a separate Prospectus.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Investor Class Prospectus | Boston Partners Global Equity Fund | MSCI World Index - Net Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

27.67%

^[1]

5 Years

rr_AverageAnnualReturnYear05

8.74%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

11.21%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

^[1]

Investor Class Prospectus | Boston Partners Global Equity Fund | MSCI World Index - Gross Return (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

28.40%

^[1]

5 Years

rr_AverageAnnualReturnYear05

9.36%

^[1]

Since Inception

rr_AverageAnnualReturnSinceInception

11.85%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

^[1]

Investor Class Prospectus | Boston Partners Global Equity Fund | Investor Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

BPGRX

Management Fees

rr_ManagementFeesOverAssets

0.90%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.13%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.29%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.09%)

^[3]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.20%

One Year

rr_ExpenseExampleYear01

$ 122

Three Years

rr_ExpenseExampleYear03

348

Five Years

rr_ExpenseExampleYear05

591

Ten Years

rr_ExpenseExampleYear10

$ 1,288

Investor Class Prospectus | Boston Partners Global Equity Fund | Institutional Class

Prospectus [Line Items]

rr_ProspectusLineItems

Annual Return 2012

rr_AnnualReturn2012

15.34%

Annual Return 2013

rr_AnnualReturn2013

32.67%

Annual Return 2014

rr_AnnualReturn2014

4.34%

Annual Return 2015

rr_AnnualReturn2015

0.80%

Annual Return 2016

rr_AnnualReturn2016

8.50%

Annual Return 2017

rr_AnnualReturn2017

20.37%

Annual Return 2018

rr_AnnualReturn2018

(13.15%)

Annual Return 2019

rr_AnnualReturn2019

18.77%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.70%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.86%)

1 Year

rr_AverageAnnualReturnYear01

18.77%

5 Years

rr_AverageAnnualReturnYear05

6.31%

Since Inception

rr_AverageAnnualReturnSinceInception

10.15%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

Investor Class Prospectus | Boston Partners Global Equity Fund | Institutional Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

18.37%

^[4]

5 Years

rr_AverageAnnualReturnYear05

5.60%

^[4]

Since Inception

rr_AverageAnnualReturnSinceInception

9.37%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

^[4]

Investor Class Prospectus | Boston Partners Global Equity Fund | Institutional Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

11.39%

5 Years

rr_AverageAnnualReturnYear05

4.85%

Since Inception

rr_AverageAnnualReturnSinceInception

8.10%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

[1] Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.20% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.20%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.20% or the expense cap then in effect, or whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Prospectus [Line Items]

rr_ProspectusLineItems

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2019

Entity Registrant Name

dei_EntityRegistrantName

RBB FUND, INC.

Entity Central Index Key

dei_EntityCentralIndexKey

0000831114

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Feb. 28, 2020

Document Effective Date

dei_DocumentEffectiveDate

Feb. 28, 2020

Prospectus Date

rr_ProspectusDate

Feb. 28, 2020

Investor Class Prospectus | Boston Partners Long/Short Equity Fund

Prospectus [Line Items]

rr_ProspectusLineItems

Risk/Return [Heading]

rr_RiskReturnHeading

SUMMARY SECTION — BOSTON PARTNERS LONG/SHORT EQUITY FUND

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation while reducing exposure to general equity market risk. The Fund seeks a total return greater than that of the S&P 500^® Index over a full market cycle.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell Investor Class shares of the Fund.

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

February 28, 2021

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 64% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

64.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage. The Fund invests, both long and short, in securities principally traded in the United States markets. The Fund may invest in securities of companies operating for three years or less (“unseasoned issuers”). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the United States equity market generally. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities.

Under normal circumstances, the Adviser expects that the Fund’s long positions will not exceed approximately 125% of the Fund’s net assets.

The Fund’s long and short positions may involve (without limit) equity securities of foreign issuers that are traded in the markets of the United States. The Fund may also invest up to 20% of its total assets directly in equity securities of foreign issuers.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations. High yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund’s assets could impede portfolio management or the Fund’s ability to meet redemption requests or other current obligations.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Risk Lose Money [Text]

rr_RiskLoseMoney

You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Equity Fund’s Investor Class. The bar chart below shows you how the performance of the Fund’s Investor Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Investor Class has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	13.42% (quarter ended December 31, 2010)
Worst Quarter:	-9.99% (quarter ended June 30, 2010)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns for the Periods Ended December 31, 2019

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund’s Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods. Although the Fund compares its average total return to a broad-based securities market index, the Fund seeks returns that are not correlated to securities market returns. The Fund seeks to achieve a 12-15% return over a full market cycle; however, there can be no guarantee that such returns will be achieved.

Investor Class Prospectus | Boston Partners Long/Short Equity Fund | S&P 500® Value Index (reflects no deduction for fees, expenses or taxes)

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

31.49%

5 Years

rr_AverageAnnualReturnYear05

11.70%

10 Years

rr_AverageAnnualReturnYear10

13.56%

Investor Class Prospectus | Boston Partners Long/Short Equity Fund | Investor Class

Prospectus [Line Items]

rr_ProspectusLineItems

Trading Symbol

dei_TradingSymbol

BPLEX

Management Fees

rr_ManagementFeesOverAssets

2.25%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.21%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.93%

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.50%)

^[1]

Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.43%

One Year

rr_ExpenseExampleYear01

$ 246

Three Years

rr_ExpenseExampleYear03

810

Five Years

rr_ExpenseExampleYear05

1,401

Ten Years

rr_ExpenseExampleYear10

$ 3,001

Annual Return 2010

rr_AnnualReturn2010

26.14%

Annual Return 2011

rr_AnnualReturn2011

5.63%

Annual Return 2012

rr_AnnualReturn2012

12.25%

Annual Return 2013

rr_AnnualReturn2013

7.59%

Annual Return 2014

rr_AnnualReturn2014

4.49%

Annual Return 2015

rr_AnnualReturn2015

(1.39%)

Annual Return 2016

rr_AnnualReturn2016

22.19%

Annual Return 2017

rr_AnnualReturn2017

2.55%

Annual Return 2018

rr_AnnualReturn2018

(15.70%)

Annual Return 2019

rr_AnnualReturn2019

8.85%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.42%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.99%)

1 Year

rr_AverageAnnualReturnYear01

8.85%

5 Years

rr_AverageAnnualReturnYear05

2.54%

10 Years

rr_AverageAnnualReturnYear10

6.66%

Investor Class Prospectus | Boston Partners Long/Short Equity Fund | Investor Class | After Taxes on Distributions

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

6.19%

^[2]

5 Years

rr_AverageAnnualReturnYear05

1.13%

^[2]

10 Years

rr_AverageAnnualReturnYear10

4.84%

^[2]

Investor Class Prospectus | Boston Partners Long/Short Equity Fund | Investor Class | After Taxes on Distributions and Sales

Prospectus [Line Items]

rr_ProspectusLineItems

1 Year

rr_AverageAnnualReturnYear01

7.10%

5 Years

rr_AverageAnnualReturnYear05

1.89%

10 Years

rr_AverageAnnualReturnYear10

5.06%

[1] Effective February 28, 2020, the Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Investor Class shares exceeds 2.21% of the average daily net assets attributable to the Fund's Investor Class shares. Because dividend expenses on short sales, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 2.21%. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 2.21% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement. Prior to February 28, 2020, the Fund's Investor Class fee cap was 2.75%.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

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Institutional Class Prospectus | Boston Partners Long/Short Research Fund

SUMMARY SECTION — BOSTON PARTNERS LONG/SHORT RESEARCH FUND

Investment Objective

The Fund seeks to provide long-term total return.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners Long/Short Research Fund Institutional Class
Management Fees	1.25%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.13%
Dividend expense on short sales	0.77%
Interest expense on borrowings	none
Total Annual Fund Operating Expenses	2.15%	[1]

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | Boston Partners Long/Short Research Fund | Institutional Class | USD ($)	2,181	6,730	11,543	24,827

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 60% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund uses a hedged strategy. The Fund actively invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales (i.e. sales of securities the Fund does not own) are invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. Short sales are considered speculative transactions and a form of leverage.

The Fund invests, both long and short, in equity securities issued by large-, mid- and small (or “micro”) cap companies, as well as other instruments that are convertible into equity securities. Selling securities short is a form of leverage. Equity securities in which the Fund may invest include exchange-traded and over-the-counter common and preferred stocks, warrants, rights, convertible securities, depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies and real estate investment trusts (“REITs”), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less (“unseasoned issuers”). The Fund may also invest in depositary receipts and equity securities of foreign companies (denominated in either U.S. dollars or foreign currencies), put and call options, futures, indexed securities and fixed-income securities (including bonds, notes, asset-backed securities, convertible securities, Eurodollar and Yankee dollar instruments, preferred stocks and money market instruments) and high yield securities (commonly referred to as “junk bonds”). Fixed income securities in which the Fund invests include those rated between AAA and D by a nationally recognized statistical rating organization, or deemed of comparable quality by the Adviser. The Adviser may also temporarily invest uninvested cash in money market funds and similar collective investment vehicles. The Fund may also seek to increase its income by lending portfolio securities.

The Adviser determines the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the U.S. equity market by investing less than 100% of its assets in net long positions. Selection of individual securities to be held long or sold short will be based on a mix of quantitative techniques and fundamental security analysis. The Adviser selects stocks on the basis of three criteria: value, fundamental business strength and momentum. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

Although the Fund seeks to follow a hedged strategy, there can be no assurance that the Fund’s portfolio or investments will be insulated from market moves or effectively hedged against risk.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest in exchange traded funds to the extent permitted by the Investment Company Act of 1940, as amended (“1940 Act”), and applicable SEC orders.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The principal derivative instruments in which the Fund invests are futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps. The Fund’s investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund’s investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Exchange-Traded Fund Risk. Exchange-traded funds (“ETFs”) are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and financial practices.

● High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations (of any rating, including defaulted securities and unrated securities), including bonds and debentures, issued by corporations and business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as “junk bonds” and are not considered to be investment grade.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● Indexed Securities Risk. The Fund may invest in indexed securities whose value is linked to securities indices. Most such securities have values that rise and fall according to the change in one or more specified indices and may have characteristics similar to direct investments in the underlying securities. Depending on the index, such securities may have greater volatility than the market as a whole.

● Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may be incorrect in the stocks it buys and believes to be undervalued and in stocks it sells short and believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

● Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund’s performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. A portfolio turnover rate of 100% is considered to be high. The annual portfolio turnover rate for the Fund is not expected to exceed 300%; however, it may be higher if the Adviser believes it will improve the Fund’s performance.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Short Sales Risk. Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund’s obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales “against the box” may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not “against the box” involve a form of investment leverage, and the amount of the Fund’s loss on a short sale is potentially unlimited.

● Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

● Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Research Fund’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	8.37% (quarter ended December 31, 2011)
Worst Quarter:	-9.89% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Institutional Class Prospectus - Boston Partners Long/Short Research Fund		1 Year	5 Years	Since Inception	Inception Date
Institutional Class		12.58%	3.11%	6.83%	Sep. 30, 2010
Institutional Class | After Taxes on Distributions	[1]	11.97%	2.57%	6.45%	Sep. 30, 2010
Institutional Class | After Taxes on Distributions and Sales		7.87%	2.37%	5.48%	Sep. 30, 2010
S&P 500® Index (reflects no deduction for fees, expenses or taxes)		31.49%	11.70%	14.26%	Sep. 30, 2010

[1] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to forgo all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) exceeds 1.50% of the average daily net assets attributable to the Fund's Institutional Class shares. Because short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 1.50%. This contractual limitation is in effect until at least February 28, 2021 and may not be terminated without Board approval. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.50% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Institutional Class Prospectus | Boston Partners Global Equity Fund

SUMMARY SECTION — BOSTON PARTNERS GLOBAL EQUITY FUND

Investment Objective

The Fund seeks to provide long-term capital growth.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners Global Equity Fund Institutional Class
Management Fees	0.90%
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.13%
Acquired fund fees and expenses	0.01%	[1]
Total Annual Fund Operating Expenses	1.04%
Fee Waivers and/or Expense Reimbursements	(0.09%)	[2]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	0.95%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | Boston Partners Global Equity Fund | Institutional Class | USD ($)	969	3,220	5,653	12,629

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 97% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity- related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by the Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Adviser applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Adviser considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer's inherent value.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund's principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears.  Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

● Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

● Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Exchange-Traded Fund Risk. Exchange-traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF typically represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. Some ETFs are actively-managed by an investment adviser and/or sub-advisers. Actively-managed ETFs are subject to the risk of poor investment selection. The Fund may incur brokerage fees in connection with its purchase of ETF shares. The purchase of shares of ETFs may result in duplication of expenses, including advisory fees, in addition to the Fund's own expenses. Certain ETFs may be thinly traded and experience large spreads between the "ask" price quoted by a seller and the "bid" price offered by a buyer.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund's ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Micro-Cap Companies Risk. Micro-cap stocks may be very sensitive to changing economic conditions and market downturns because the issuers often have narrow markets for their products or services, fewer product lines, and more limited managerial and financial resources than larger issuers. The stocks of micro-cap companies may therefore be more volatile and the ability to sell them at a desirable time or price may be more limited.

● Mid-Cap Companies Risk. The stocks of mid-sized companies may be subject to more abrupt or erratic market movements than stocks of larger, more established companies.

● Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

● REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidation, interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500® Index. In addition, REITs could possibly fail to (i) qualify for favorable tax treatment under applicable tax law or (ii) maintain their exemptions from registration under the 1940 Act.

● Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

● Small-Cap Companies Risk. The stocks of smaller companies may be subject to more abrupt, erratic market movements than stocks of larger, more established companies. Small companies may have limited product lines or financial resources, or may be dependent on a small or inexperienced management group, and their securities may trade less frequently and in lower volume than securities of larger companies, which could lead to higher transaction costs. Generally, the smaller the company size, the greater the risk.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Global Equity Fund's Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	11.70% (quarter ended March 31, 2012)
Worst Quarter:	-14.86% (quarter ended December 31, 2018)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and since inception periods to the average annual total returns of broad-based securities market indices for the same periods.

Average Annual Total Returns - Institutional Class Prospectus - Boston Partners Global Equity Fund		1 Year	5 Years	Since Inception	Inception Date
Institutional Class		18.77%	6.31%	10.15%	Dec. 30, 2011
Institutional Class | After Taxes on Distributions	[1]	18.37%	5.60%	9.37%	Dec. 30, 2011
Institutional Class | After Taxes on Distributions and Sales		11.39%	4.85%	8.10%	Dec. 30, 2011
MSCI World Index - Net Return (reflects no deduction for fees, expenses or taxes)	[2]	27.67%	8.74%	11.21%	Dec. 30, 2011
MSCI World Index - Gross Return (reflects no deduction for fees, expenses or taxes)	[2]	28.40%	9.36%	11.85%	Dec. 30, 2011

[1] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[2] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser") has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 0.95% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.95%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 0.95% or the expense cap then in effect, or whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

[2] Effective August 31, 2019, the Fund changed its primary index from the MSCI World Index - Gross Return to the MSCI World Index - Net Return. Net total return indices reinvest dividends after the deduction of withholding taxes, using (for international indices) a tax rate applicable to non-resident institutional investors who do not benefit from double taxation treaties.

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Abbey Capital | Abbey Capital Futures Strategy Fund

SUMMARY SECTION

Investment Objective

The investment objective of the Abbey Capital Futures Strategy Fund (the “Fund”) is to seek long-term capital appreciation.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund (the “Shares”). You may qualify for sales charge discounts if you invest, or agree to invest in the future, at least $25,000 in Class A Shares or at least $250,000 in Class T Shares of the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information – Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information – Reducing or Eliminating the Front-End Sales Charge.” Financial intermediaries may impose different sales charge waivers for Class A Shares and Class T Shares, and these variations are described in Appendix A of the Prospectus. Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - Abbey Capital - Abbey Capital Futures Strategy Fund	Class I Shares	Class A Shares		Class C Shares		Class T Shares
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	none	5.75%		none		2.50%
Maximum Deferred Sales Charge (Load)	none	none	[1]	1.00%	[2]	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends	none	none		none		none
Redemption Fee (as a percentage of amount redeemed, if applicable)	none	none		none		none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Abbey Capital - Abbey Capital Futures Strategy Fund		Class I Shares	Class A Shares	Class C Shares	Class T Shares
Management Fees	[1]	1.77%	1.77%	1.77%	1.77%
Distribution and/or Service (12b-1) Fees		none	0.25%	1.00%	0.25%
Other Expenses		0.12%	0.12%	0.12%	0.12%	[2]
Total Annual Fund Operating Expenses		1.89%	2.14%	2.89%	2.14%
Fee Waivers and/or Expense Reimbursements	[3]	(0.10%)	(0.10%)	(0.10%)	(0.10%)
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	[3]	1.79%	2.04%	2.79%	2.04%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in Class A, Class C and Class T Shares, and $1,000,000 in Class I Shares, in the Fund for the time periods indicated and then redeem all of your Shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same (taking into account the contractual expense limitation until its expiration). Although your actual costs may be higher or lower, based on these assumptions your costs of investing in the Fund would be:

Expense Example - Abbey Capital - Abbey Capital Futures Strategy Fund - USD ($)	One Year	Three Years	Five Years	Ten Years
Class I Shares	18,187	58,423	101,201	220,344
Class A Shares	770	1,197	1,649	2,898
Class C Shares	382	885	1,514	3,207
Class T Shares	452	894	1,362	2,653

You would pay the following expenses on Class C Shares if you did not redeem your shares at the end of the period:

Expense Example, No Redemption	One Year	Three Years	Five Years	Ten Years
Abbey Capital | Abbey Capital Futures Strategy Fund | Class C Shares | USD ($)	282	885	1,514	3,207

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 0% of the average value of its portfolio. In accordance with industry practice, derivative instruments and instruments with a maturity of one year or less at the time of acquisition are excluded from the calculation of the portfolio turnover rate, which leads to the 0% portfolio turnover rate reported above. If those instruments were included in the calculation, the Fund would have a high portfolio turnover rate.

Principal Investment Strategies

The Fund seeks to achieve its investment objective by allocating its assets between a “Managed Futures” strategy and a “Fixed Income” strategy.

The Managed Futures strategy will be achieved by the Fund investing a portion of its assets in Abbey Capital Onshore Series LLC, a wholly-owned and controlled Delaware series limited liability company (the “Onshore Subsidiary”) and up to 25% of its total assets in Abbey Capital Master Offshore Fund Limited, a wholly-owned and controlled subsidiary of the Fund organized under the laws of the Cayman Islands (the “Cayman Subsidiary”). The Cayman Subsidiary will in turn invest all or substantially all of its assets in segregated portfolios of Abbey Capital Offshore Fund SPC (the “SPC” and, together with the Onshore Subsidiary and the Cayman Subsidiary, the “Subsidiaries”), a wholly-owned and controlled segregated portfolio company incorporated under the laws of the Cayman Islands. The Cayman Subsidiary will serve solely as an intermediate entity through which the Fund will invest in the SPC. The Cayman Subsidiary makes no independent investment decisions and has no investment or other discretion over the Fund’s investable assets. The Adviser may allocate assets of the SPC and the Onshore Subsidiary to multiple Managed Futures portfolios (the “Segregated Portfolios”) that include investment styles or sub-strategies such as (i) trend following, (ii) discretionary, fundamentals-based investing with a focus on macroeconomic analysis, (iii) strategies that pursue both fundamental and technical trading approaches, (iv) other specialized approaches to specific or individual market sectors such as equities, interest rates, metals, agricultural and soft commodities, and (v) systematic trading strategies which incorporate technical and fundamental variables.

The Managed Futures strategy investments are designed to achieve capital appreciation in the financial and commodities futures markets. The Adviser intends to allocate the assets of the SPC and the Onshore Subsidiary to one or more Trading Advisers to manage in percentages determined at the discretion of the Adviser. Each Trading Adviser will manage one or more of its own Segregated Portfolios. Each Trading Adviser invests according to a Managed Futures strategy in one or a combination of (i) options, (ii) futures, (iii) forwards, (iv) spot contracts, or (v) swaps, including total return swaps, each of which may be tied to (i) commodities, (ii) financial indices and instruments, (iii) foreign currencies, or (iv) equity indices. All commodities futures and commodities-related investments will be made in the Segregated Portfolios of the SPC. Each current Trading Adviser is registered with the U.S. Commodity Futures Trading Commission (the “CFTC”) as a Commodity Trading Advisor. Trading Advisers that are not registered with the SEC as investment advisers provide advice only regarding matters that do not involve securities.

The Fixed Income strategy invests the Fund’s assets primarily in investment grade fixed income securities (of all durations and maturities) in order to generate interest income and capital appreciation, which may add diversification to the returns generated by the Fund’s Managed Futures strategy. The Fund must set aside liquid assets, or engage in other SEC or staff-approved measures, to “cover” open positions with respect to certain kinds of derivative instruments. The Fixed Income strategy investments may be used to help cover the Fund’s derivative positions.

The Fund’s Adviser seeks returns, in part, by (i) using Managed Futures strategy investments that are not expected to have returns that are highly correlated to the broad equity market, and (ii) through actively managed Fixed Income strategy investments that are not expected to have returns that are highly correlated to the broad equity market or the Managed Futures strategy. The Adviser believes that utilizing non-correlated strategies may mitigate losses in generally declining markets. However, there can be no assurance that losses will be avoided. Investment strategies that have historically been non-correlated or demonstrated low correlations to one another or to major world financial market indices may become correlated at certain times, such as during a liquidity crisis in global financial markets.

The trading strategies employ several different trading styles using different research and trading methodologies, in a wide range of global financial and commodity markets operating over multiple time frames. Many of the styles use systematic, automated trading systems, using a combination of mathematical, statistical, technical analysis, pattern recognition and macroeconomic models aimed at profiting from market trends of different durations. Trading Advisers may use discretionary approaches aimed at identifying value investments and turning points in trends. All Trading Advisers utilize a disciplined approach to risk management. The Adviser and Trading Advisers from time to time will employ hedging techniques. Key principles of the Fund’s sell discipline include predetermined relative-value objectives for sectors, issuers and specific securities, pricing performance or fundamental performance that varies from expectations, deteriorating fundamentals, overvaluation and alternative investments offering the opportunity to achieve more favorable risk-adjusted returns.

The markets traded include bonds, money markets, foreign exchange markets and commodity markets. Most of the trading is done in derivative markets, usually listed futures markets, but some trading in cash markets may take place when this is the most effective way to enter or exit a trading position. Both long and short positions will be taken in all markets traded. Contracts are positioned either long or short based on various characteristics related to their prices. For example, the Fund may short a particular underlying security or instrument if the Adviser or a Trading Adviser believes the price of the underlying security or instrument will decrease. The Fund invests in U.S. and non-U.S. markets and in developed and emerging markets.

As much of the trading within the Fund is in futures markets, the Fund is likely to have cash balances surplus to margin requirements. The cash portfolio will be invested on a short-term, highly liquid, basis, to meet margin calls on the futures positions.

The Fund is “non-diversified” for purposes of the Investment Company Act of 1940, as amended, (the “1940 Act”) which means that the Fund may invest in fewer securities at any one time than a diversified fund. The Fund may not invest more than 15% of its net assets in illiquid securities. The Fund’s investments in certain derivative instruments and its short selling activities involve the use of leverage.

Generally, the SPC invests primarily in commodity futures but it may also invest in financial futures, options, forwards, spot contracts and swap contracts, fixed income securities, pooled investment vehicles, including those that are not registered pursuant to the 1940 Act and other investments intended to serve as margin or collateral for the SPC’s derivative positions. The Onshore Subsidiary only invests in financial futures, options, forwards, spot contracts and swap contracts, fixed income securities, pooled investment vehicles, including those that are not registered pursuant to the 1940 Act, and other investments intended to serve as margin or collateral for derivative positions. The Fund invests in the SPC in order to gain exposure to the commodities markets within the limitations of the federal tax laws, rules and regulations that apply to registered investment companies. Unlike the Fund and Onshore Subsidiary, the SPC may invest without limitation in commodity-linked derivatives, however, the SPC complies with the same 1940 Act asset coverage requirements with respect to its investments in commodity-linked derivatives that are applicable to the Fund’s transactions in derivatives. The Fund complies with Section 8 and Section 18 of the 1940 Act, governing investment policies and capital structure and leverage, respectively, on an aggregate basis with the Subsidiaries. The Subsidiaries also comply with Section 17 of the 1940 Act relating to affiliated transactions and custody.

In addition, to the extent applicable to the investment activities of the Subsidiaries, the Subsidiaries are subject to the same fundamental investment restrictions and will follow the same compliance policies and procedures as the Fund. Unlike the Fund, none of the Subsidiaries will seek to qualify as a regulated investment company (“RIC”) under Subchapter M of Subtitle A, Chapter 1, of the Internal Revenue Code of 1986, as amended (the “Code”). The Fund is, directly or indirectly, the sole shareholder of each Subsidiary and does not expect shares of the Subsidiaries to be offered or sold to other investors.

Principal Investment Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

The principal risk factors affecting shareholders’ investments in the Fund (and, indirectly, in the Subsidiaries) are set forth below.

● Commodity Sector Risk: Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative instruments may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments. The prices of energy, industrial metals, precious metals, agriculture and livestock sector commodities may fluctuate widely due to factors such as changes in value, supply and demand and governmental regulatory policies. The commodity-linked securities in which the Fund invests may be issued by companies in the financial services sector, and events affecting the financial services sector may cause the Fund’s Share value to fluctuate.

● Counterparty Risk: Counterparty risk is the risk that the other party(s) to an agreement or a participant to a transaction, such as a broker or the futures commission merchant, might default on a contract or fail to perform by failing to pay amounts due or failing to fulfill the obligations of the contract or transaction.

● Credit Risk: Credit risk refers to the possibility that the issuer of the security will not be able to make principal and interest payments when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. Securities rated in the four highest categories by the rating agencies are considered investment grade but they may also have some speculative characteristics. Investment grade ratings do not guarantee that bonds will not lose value.

● Currency Risk: Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls. Forward foreign currency exchange contracts may limit potential gains from a favorable change in value between the U.S. dollar and foreign currencies. Unanticipated changes in currency pricing may result in poorer overall performance for the Fund than if it had not engaged in these contracts.

● Cyber Security Risk: Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Derivatives Risk: The Fund’s investments in derivative instruments including options, forward currency exchange contracts, swaps and futures, which may be leveraged, may result in losses. Investments in derivative instruments may result in losses exceeding the amounts invested.

● Emerging Markets Risk: Investment in emerging market securities involves greater risk than that associated with investment in foreign securities of developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

● Fixed Income Securities Risk: Fixed income securities in which the Fund may invest are subject to certain risks, including: interest rate risk, prepayment risk and credit/default risk. Interest rate risk involves the risk that prices of fixed income securities will rise and fall in response to interest rate changes. Prepayment risk involves the risk that in declining interest rate environments prepayments of principal could increase and require the Fund to reinvest proceeds of the prepayments at lower interest rates. Credit risk involves the risk that the credit rating of a security may be lowered.

● Foreign Investments Risk: International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through “sponsored” or “unsponsored” facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders.

● Forward and Futures Risk: The successful use of forward and futures contracts draws upon the Adviser’s and Trading Advisers’ skill and experience with respect to such instruments and are subject to special risk considerations. The primary risks associated with the use of futures contracts are (a) the imperfect correlation between the change in market value of instruments held by the Fund and the price of the forward or futures contract; (b) possible lack of a liquid secondary market, and possible regulatory position limits and restrictions, for a forward or futures contract and the resulting inability to close a forward or futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s and Trading Advisers’ inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; (e) the possibility that the counterparty will default in the performance of its obligations; and (f) if the Fund has insufficient cash, it may have to sell securities from its portfolio to meet daily variation margin requirements, and the Fund may have to sell securities at a time when it may be disadvantageous to do so.

● Hedging Transactions Risk: The Adviser and Trading Advisers from time to time employ various hedging techniques. The success of the Fund’s hedging strategy will be subject to the Adviser’s and Trading Advisers’ ability to correctly assess the degree of correlation between the performance of the instruments used in the hedging strategy and the performance of the investments in the portfolio being hedged. Since the characteristics of many securities change as markets change or time passes, the success of the Fund’s hedging strategy will also be subject to the Adviser’s and Trading Advisers’ ability to continually recalculate, readjust, and execute hedges in an efficient and timely manner. For a variety of reasons, the Adviser and Trading Advisers may not seek to establish a perfect correlation between such hedging instruments and the portfolio holdings being hedged. Such imperfect correlation may prevent the Fund from achieving the intended hedge or expose the Fund to risk of loss. In addition, it is not possible to hedge fully or perfectly against any risk, and hedging entails its own cost.

● High Portfolio Turnover Risk: The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions, and cause higher levels of current tax liability to shareholders in the Fund.

● Interest Rate Risk: Interest rate risk is the risk that prices of fixed income securities generally increase when interest rates decline and decrease when interest rates increase. The Fund may lose money if short term or long term interest rates rise sharply or otherwise change in a manner not anticipated by the Adviser and Trading Advisers. It is likely there will be less governmental action in the near future to maintain low interest rates. The negative impact on fixed income securities from the resulting rate increases for that and other reasons could be swift and significant.

● Leveraging Risk: Investments in derivative instruments may give rise to a form of leverage. Trading Advisers may engage in speculative transactions which involve substantial risk and leverage, such as making short sales. The use of leverage by the Adviser and Trading Advisers may increase the volatility of the Fund. These leveraged instruments may result in losses to the Fund or may adversely affect the Fund’s net asset value (“NAV”) or total return, because instruments that contain leverage are more sensitive to changes in interest rates. The Fund may also have to sell assets at inopportune times to satisfy its obligations in connection with such transactions.

● Management Risk: The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Manager Risk: If the Adviser and Trading Advisers make poor investment decisions, it will negatively affect the Fund’s investment performance.

● Market Risk: The NAV of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money.

● Multi-Manager Dependence Risk: The success of the Fund’s investment strategy depends both on the Adviser’s ability to select Trading Advisers and to allocate assets to those Trading Advisers and on each Trading Adviser’s ability to execute the relevant strategy and select investments for the Fund and the Subsidiaries. The Trading Advisers’ investment styles may not always be complementary, which could adversely affect the performance of the Fund.

● New Adviser Risk: The Trading Advisers may be newly registered or not registered with the SEC and/or have not previously managed a mutual fund. Accordingly, investors in the Fund bear the risk that a Trading Adviser’s inexperience may limit its effectiveness.

● Non-Diversification Risk: The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

● Options Risk: Purchasing and writing put and call options are highly specialized activities and entail greater than ordinary investment risks. The Fund may not fully benefit from or may lose money on an option if changes in its value do not correspond as anticipated to changes in the value of the underlying securities.

● Quantitative Trading Strategies Risk: The Adviser and Trading Advisers may use quantitative methods to select investments. Securities or other investments selected using quantitative methods may perform differently from the market as a whole or from their expected performance for many reasons, including factors used in building the quantitative analytical framework, the weights placed on each factor, and changing sources of market returns, among others. Any errors or imperfections in quantitative analyses or models, or in the data on which they are based, could adversely affect the ability of the Adviser or a Trading Adviser to use such analyses or models effectively, which in turn could adversely affect the Fund’s performance. There can be no assurance that these methodologies will help the Fund to achieve its investment objective.

● Short Sales Risk: Short sales of securities may result in gains if a security’s price declines, but may result in losses if a security’s price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund’s obligations to provide collateral to the lender and set aside assets to cover the open position. The Fund may engage in short sales that are either “uncovered” or “against the box.” A short sale is “against the box” if at all times during which the short position is open, the Fund owns at least an equal amount of the securities or securities convertible into, or exchangeable without further consideration for, securities of the same issue as the securities that are sold short. Short sales “against the box” may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not “against the box” involve a form of investment leverage, and the amount of the Fund’s loss on a short sale is potentially unlimited.

● Subsidiary Risk: By investing in the Subsidiaries, the Fund is indirectly exposed to the risks associated with each Subsidiary’s investments. The derivatives and other investments held by the Subsidiaries are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund. The Subsidiaries are not registered under the 1940 Act, and, unless otherwise noted in this Prospectus, are not subject to all the investor protections of the 1940 Act. Changes in the laws of the United States, Delaware and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiaries to continue to operate as they currently do and could adversely affect the Fund.

● Tax Risk: In order to qualify as a RIC, the Fund must meet certain requirements regarding the source of its income, the diversification of its assets and the distribution of its income. Under the test regarding the source of a RIC’s income, at least 90% of the gross income of the RIC each year must be qualifying income, which consists of dividends, interest, gains on investment assets and other categories of investment income. In 2006, the Internal Revenue Service (“IRS”) published a ruling that income realized from swaps with respect to a commodities index would not be qualifying income. The Fund’s investment in the SPC (via the Cayman Subsidiary) is expected to provide the Fund with exposure to the commodities markets within the limitations of the Code for qualification as a RIC, but there is a risk that the IRS could assert that the income derived from the investment in the SPC and certain commodity-linked structured notes will not be considered qualifying income for purposes of the Fund remaining qualified as a RIC for U.S. federal income tax purposes. If the Fund were to fail to qualify as a RIC and became subject to federal income tax, shareholders of the Fund would be subject to diminished returns. Changes in the laws of the United States, Delaware and/or the Cayman Islands could result in the inability of the Fund and/or its Subsidiaries to operate as described in this Prospectus and the SAI and could adversely affect the Fund. For example, the Cayman Islands does not currently impose any income, corporate or capital gains tax or withholding tax on the Cayman Subsidiary or the SPC. If Cayman Islands law changes such that the Cayman Subsidiary and/or the SPC must pay Cayman Islands taxes, Fund shareholders would likely suffer decreased investment returns.

Performance Information

The following performance information provides some indication of the risks of investing in the Fund. The bar chart shows the performance of the Fund’s Class I Shares from year to year. Performance information represents only past performance, before and after taxes, and does not necessarily indicate future results. Updated performance information is available online at www.abbeycapital.com or by calling 1-844-261-6484 (toll free).

Abbey Capital Futures Strategy Fund – Class I Shares Total Returns for Calendar Years Ended December 31

During the period shown in the chart, the highest quarterly return was 8.86% (for the quarter ended March 31, 2015) and the lowest quarterly return was -4.90% (for the quarter ended June 30, 2015).

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

The following table, which includes all applicable sales loads, compares the average annual total returns of the Class I Shares, Class A Shares and Class C Shares for the one-year, five-year, and since inception periods to a broad-based market index for the same periods. Average annual returns for Class T Shares are not included because they had not commenced operations prior to the date of this Prospectus. The returns for Class T Shares would be substantially similar to returns for Class I Shares because the shares are invested in the same portfolio of securities, and would differ only to the extent that the classes have different expenses.

Average Annual Total Returns - Abbey Capital - Abbey Capital Futures Strategy Fund		1 Year	5 Years	Since Inception		Inception Date
Class I Shares		8.85%	0.44%	3.57%		Jul. 01, 2014
Class I Shares | After Taxes on Distributions	[1]	5.51%	(0.22%)	2.79%		Jul. 01, 2014
Class I Shares | After Taxes on Distributions and Sales	[1]	5.46%	0.09%	2.45%		Jul. 01, 2014
Class A Shares		2.40%	(0.99%)	2.21%	[2]	Jul. 01, 2014
Class C Shares		7.75%	(0.55%)	2.55%	[2]	Jul. 01, 2014
S&P 500® Total Return Index (reflects no deduction for fees, expenses and taxes)		31.49%	11.70%	11.64%		Jul. 01, 2014

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Class A Shares made within 12 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The CDSC applies to redemptions of Class C Shares made within 12 months of purchase and will be assessed on an amount equal to the lesser of the offering price at the time of purchase of the shares redeemed and the net asset value of the shares redeemed at the time of redemption.

[1] Management Fees include advisory fees paid to both Abbey Capital Limited (the "Adviser") and one or more trading advisers (the "Trading Advisers"). There are no performance fees charged by the Adviser or Trading Advisers either at the Fund or at the Fund's wholly-owned Subsidiaries.

[2] "Other Expenses" for Class T Shares, which had not commenced operations as of the date of this Prospectus, are estimated for the current fiscal year.

[3] The Adviser has contractually agreed to waive its advisory fee and/or reimburse expenses in order to limit Total Annual Fund Operating Expenses (excluding certain items discussed below) to 1.79%, 2.04%, 2.79% and 2.04% of the Fund's average daily net assets attributable to Class I Shares, Class A Shares, Class C Shares and Class T Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total Annual Fund Operating Expenses to exceed 1.79%, 2.04%, 2.79% or 2.04%, as applicable: acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 for Class I Shares, Class A Shares, Class C Shares and Class T Shares, and may not be terminated prior to that date without the approval of the Board of Directors of The RBB Fund, Inc. (the "Company"). If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.79%, 2.04%, 2.79% and 2.04%, as applicable, the Adviser may recoup any waived or reimbursed amounts from the Fund within three years from the date on which such waiver or reimbursement was made by the Adviser, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In certain cases, the figure representing "Return after Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Class I Shares only. After-tax returns for Class A Shares, Class C Shares and Class T Shares will vary.

[2] Class I Shares commenced operations on July 1, 2014, Class A Shares commenced operations on August 29, 2014, and Class C Shares commenced operations on October 6, 2015. Performance shown prior to inception of the Class A Shares and Class C Shares is based on the performance of Class I Shares, adjusted for the higher expenses applicable to Class A Shares and Class C Shares, respectively.

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Institutional Class Prospectus | Boston Partners Small Cap Value Fund II

SUMMARY SECTION — BOSTON PARTNERS SMALL CAP VALUE FUND II

Investment Objective

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell Institutional Class shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Institutional Class shares of the Fund, which are not reflected in the tables or the examples below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)  

Annual Fund Operating Expenses	Institutional Class Prospectus Boston Partners Small Cap Value Fund II Institutional Class
Management Fees	0.95%	[1]
Distribution and/or Service (12b-1) Fees	none
Other Expenses	0.21%
Acquired fund fees and expenses	0.01%	[2]
Total Annual Fund Operating Expenses	1.17%
Fee Waivers and/or Expense Reimbursements	(0.07%)	[3]
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements	1.10%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	One Year	Three Years	Five Years	Ten Years
Institutional Class Prospectus | Boston Partners Small Cap Value Fund II | Institutional Class | USD ($)	1,121	3,647	6,369	14,142

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the fiscal year ended August 31, 2019, the portfolio turnover rate for the Fund was 29% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers with small market capitalizations and identified by the Adviser as having value characteristics. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Value Index. The Russell 2000^® Value Index is an unmanaged index that contains stocks from the Russell 2000^® Index with less than average growth orientation. As of November 30, 2019, the median market capitalization of this index was $666 million and the largest stock was $6.7 billion. Please note that this range is as of a particular point in time and is subject to change.

The Fund generally invests in the equity securities of small companies. The Adviser will seek to invest in companies it considers to be well managed and to have attractive fundamental financial characteristics. The Adviser believes greater potential for price appreciation exists among small companies since they tend to be less widely followed by other securities analysts and thus may be more likely to be undervalued by the market. The Fund may invest from time to time a portion of its assets, not to exceed 20% (under normal conditions) at the time of purchase, in companies with larger market capitalizations.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer’s operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may also invest up to 25% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities (“IPO”). An IPO is a company’s first offering of stock to the public.

In general, the Fund’s investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund’s assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments and make investments inconsistent with its investment objective. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Foreign Custody Risk. The Fund may hold foreign securities and cash with foreign banks, agents, and securities depositories appointed by the Fund’s custodian (each a “Foreign Custodian”). Some Foreign Custodians may be recently organized or new to the foreign custody business. In some countries, Foreign Custodians may be subject to little or no regulatory oversight over or independent evaluation of their operations. Further, the laws of certain countries may place limitations on the Fund’s ability to recover its assets if a Foreign Custodian enters bankruptcy. Investments in emerging markets may be subject to even greater custody risks than investments in more developed markets. Custody services in emerging market countries are very often undeveloped and may be considerably less well-regulated than in more developed countries, and thus may not afford the same level of investor protection as would apply in developed countries.

● Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

● Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities. Less liquid securities that the Fund may want to invest in may be difficult or impossible to purchase. Federal banking regulations may also cause certain dealers to reduce their inventories of certain securities, which may further decrease the Fund’s ability to buy or sell such securities.

● IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund’s asset base is small, a significant portion of the Fund’s performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund’s assets grow, the effect of the Fund’s investments in IPOs on the Fund’s performance probably will decline, which could reduce the Fund’s performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund’s portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

● Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices do not work to achieve their desired result.

● Market Risk. The net asset value (“NAV”) of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

● Small Cap Companies Risk. The Fund will invest in smaller issuers which are more volatile and less liquid than investments in issuers with a market capitalization greater than the market capitalization of companies in the Russell 2000^® Value Index. Small market capitalization issuers are not as diversified in their business activities as issuers with market capitalizations greater than the market capitalization of companies in the Russell 2000^® Value Index and are more susceptible to changes in the business cycle.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the “pink sheets,” and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser’s judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Small Cap Value Fund II’s Institutional Class. The bar chart below shows you how the performance of the Fund’s Institutional Class has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	14.78% (quarter ended December 31, 2010)
Worst Quarter:	-20.45% (quarter ended September 30, 2011)

Average Annual Total Returns for the Periods Ended December 31, 2019

The table below compares the average annual total returns for the Fund’s Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Institutional Class Prospectus - Boston Partners Small Cap Value Fund II		1 Year	5 Years	10 Years
Institutional Class		28.02%	7.22%	10.83%
Institutional Class | After Taxes on Distributions	[1]	27.26%	6.12%	10.18%
Institutional Class | After Taxes on Distributions and Sales		17.07%	5.46%	8.87%
Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)		22.39%	6.99%	10.56%

[1] Prior to October 1, 2019, the management fee was 1.00%.

[2] Acquired fund fees and expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total annual Fund operating expenses and Total annual Fund operating expenses after fee waiver and/or expense reimbursement shown in the above table will differ from the "Financial Highlights" section of the prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as acquired fund fees and expenses.

[3] The Fund's investment adviser, Boston Partners Global Investors, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until February 28, 2021 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total annual Fund operating expenses (not including short sale dividend expense, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.10% or the expense cap then in effect, whichever is less, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Orinda | Orinda Income Opportunities Fund

SUMMARY SECTION — ORINDA INCOME OPPORTUNITIES FUND

Investment Objective

The Orinda Income Opportunities Fund (the “Fund”) seeks to maximize current income with potential for modest growth of capital.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund’s Class A shares. More information about these and other discounts is available from your financial professional and in the “Distribution of Fund Shares” section of the Fund’s Prospectus and the “Other Information Regarding Maximum Sales Charge, Purchases and Redemptions” section of the Fund’s Statement of Additional Information (“SAI”). Each financial intermediary may impose different sales charges and these variations are described in Appendix A of the Fund’s Prospectus.

Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

SHAREHOLDER FEES (fees paid directly from your investment)

Shareholder Fees - Orinda - Orinda Income Opportunities Fund	Class I	Class A	Class D
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	none	5.00%	none

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - Orinda - Orinda Income Opportunities Fund		Class I	Class A	Class D
Management Fees		1.00%	1.00%	1.00%
Distribution and/or Service (12b-1) Fees		none	0.25%	1.00%
Other Expenses		0.29%	0.33%	0.28%
Dividend and Interest Expense		0.50%	0.46%	0.52%
Acquired fund fees and expenses	[1]	0.12%	0.12%	0.12%
Total Annual Fund Operating Expenses	[1]	1.91%	2.16%	2.92%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in Class I Shares of the Fund and $10,000 in Class A and Class D Shares of the Fund (the minimum initial investment for Class A and Class D Shares is $5,000) for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that each year your investment has a 5% return and Fund operating expenses remain the same. Although your actual costs and returns might be different, your approximate costs of investing in the Fund would be:

Expense Example - Orinda - Orinda Income Opportunities Fund - USD ($)	One Year	Three Years	Five Years	Ten Years
Class I	1,940	6,000	10,316	22,327
Class A	708	1,142	1,601	2,868
Class D	295	904	1,538	3,242

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in total annual Fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 131% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund will attempt to achieve its investment objective by investing in U.S. and non-U.S. securities and investment instruments including, but not limited to, equity securities, debt securities, and derivatives. The Fund’s allocation to these various security types and asset classes will vary over time in response to changing market opportunities with the goal of maximizing current income.

The Fund may invest without limit in equity securities of issuers of any market capitalization. The types of equity securities in which the Fund will generally invest include common stocks, preferred stocks, real estate investment trusts (“REITs”), master limited partnerships (“MLPs”), rights, warrants, depositary receipts and other investment companies, including exchange-traded funds (“ETFs”). The Fund’s equity investments may also take the form of depositary receipts including American Depositary Receipts (“ADRs”), European Depositary Receipts (“EDRs”) and Global Depositary Receipts (“GDRs”). The Fund generally invests in dividend paying stocks. The Fund may invest up to 25% of its net assets in initial public offerings (“IPOs”). The Fund may also invest without limit in foreign securities, including up to 50% of its net assets in securities of issuers located in emerging markets.

The Fund will generally invest at least 50% of its net assets in REITs. As a result of its investments in REITs, the Fund will be concentrated in the real estate industry. The Fund may invest in “Rule 144A” securities, which are privately placed, restricted securities that may only be resold under certain circumstances to other qualified institutional buyers.

The Fund may invest without limit in debt securities, provided that no more than 30% of its net assets are invested in debt securities rated below investment grade (known as “junk bonds”). The types of debt securities in which the Fund may invest generally include instruments and obligations of U.S. and non-U.S. corporate and other non-governmental entities, those of U.S. and non-U.S. governmental entities, mortgage-related or mortgage-backed securities (including “sub-prime” mortgages), asset-backed securities, exchange-traded notes (“ETNs”), floating rate loans, convertible securities, inflation-linked debt securities and subordinated debt securities. The Fund invests in debt securities with a broad range of maturities and the Fund’s investments may have fixed or variable principal payments.

The Fund may invest up to 85% of its net assets in derivatives, including options, futures (such as bond, index, interest rate and currency futures, but excluding commodities futures) and swaps (such as credit-default swaps, interest rate swaps and total return swaps). These derivative instruments may be used for investment purposes, to modify or hedge the Fund’s exposure to a particular investment market related risk, to manage the volatility of the Fund, to hedge against adverse changes in the market price of securities, interest rates or currency exchange rates and as a substitute for purchasing or selling securities.

The Fund may utilize leverage (by borrowing against a line of credit for investment purposes) up to one-third of the value of its assets as part of the portfolio management process. The Fund may also sell securities short with respect to 100% of its net assets and may lend its portfolio securities to generate additional income. A short sale is the sale by the Fund of a security that it does not own in anticipation of purchasing the same security in the future at a lower price to close the short position.

The Fund will sell (or close a position in) a security when Orinda Asset Management LLC (the “Adviser”) determines that a particular security has achieved its investment expectations or the reasons for maintaining that position are no longer valid. It is expected that the Fund will have a portfolio turnover in excess of 100% on an annual basis. The Fund’s investment strategies may periodically result in a significant portion of its assets being invested in the securities of companies in the same sector of the market.

The Adviser may also invest up to 100% of the Fund’s total assets in cash, money-market instruments, bank obligations and other high-quality debt securities for temporary defensive purposes.

Summary of Principal Risks

Losing all or a portion of your investment is a risk of investing in the Fund. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

● Convertible Bond Risk. Convertible bonds are hybrid securities that have characteristics of both bonds and common stocks and are therefore subject to both debt security risks and equity risk. Convertible bonds are subject to equity risk especially when their conversion value is greater than the interest and principal value of the bond. The prices of equity securities may rise or fall because of economic or political changes and may decline over short or extended periods of time.

● Credit Risk. The issuers of the bonds and other debt securities held by the Fund may not be able to make interest or principal payments. The degree of credit risk depends on the issuer’s financial condition and on the terms of the securities.

● Currency Risk. Changes in foreign currency exchange rates will affect the value of what the Fund owns and the Fund’s share price. Generally, when the U.S. dollar rises in value against a foreign currency, an investment in that country loses value because that currency is worth fewer U.S. dollars. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. Currency markets generally are not as regulated as securities markets.

● Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

● Depositary Receipt Risk. Depositary receipts may be purchased through “sponsored” or “unsponsored” facilities. A sponsored facility is established jointly by the issuer of the underlying security and a depositary, whereas a depositary may establish an unsponsored facility without participation by the issuer of the depositary security. Holders of unsponsored depositary receipts generally bear all the costs of such facilities and the depositary of an unsponsored facility frequently is under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through voting rights to the holders of such receipts of the deposited securities. In addition, investment in ADRs, EDRs and GDRs may be less liquid than the underlying shares in their primary trading market.

● Derivatives Risk. The Fund’s use of derivatives (which may include options, futures and swaps, among others) may reduce the Fund’s returns and/or increase volatility. Derivatives involve the risk of improper valuation, the risk of ambiguous documentation, and the risk that changes in the value of the derivative may not correlate perfectly with the underlying security. Derivatives are also subject to market risk, interest rate risk, credit risk, counterparty risk and liquidity risk. Derivatives may be more sensitive to changes in economic or market conditions than other types of investments and could result in losses that significantly exceed the Fund’s original investment.

● Exchange-Traded Fund and Mutual Fund Risk. When the Fund invests in an ETF or mutual fund, it will bear additional expenses based on its pro rata share of the ETFs or mutual fund’s operating expenses, including the potential duplication of management fees. The risk of owning an ETF or mutual fund generally reflects the risks of owning the underlying securities the ETF or mutual fund holds. The Fund also will incur brokerage costs when it purchases ETFs. Index ETFs may not track their underlying indices.

● Exchange-Traded Note Risk. The value of an ETN may be influenced by time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in the underlying securities’ markets, changes in the applicable interest rates, changes in the issuer’s credit rating and economic, legal, political or geographic events that affect the referenced index. In addition, the notes issued by ETNs and held by the Fund are unsecured debt of the issuer.

● Fixed Income Securities Risk. Fixed income securities are subject to interest rate risk and credit risk. There is also the risk that an issuer may “call,” or repay, its high yielding bonds before their maturity dates.

● Foreign and Emerging Market Securities Risk. Foreign investments may carry risks associated with investing outside the United States, such as currency fluctuation, economic or financial instability, lack of timely or reliable financial information or unfavorable political or legal developments. Those risks are increased for investments in emerging markets.

● Futures Risk. The value of a futures contract tends to increase and decrease in correlation with the value of the underlying instrument. Risks of futures contracts may arise from an imperfect correlation between movements in the price of the futures and the price of the underlying instrument. The Fund’s use of futures contracts (and related options) exposes the Fund to leverage risk because of the small margin requirements relative to the value of the futures contract. While futures contracts are generally liquid instruments, under certain market conditions they may become illiquid. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures could exceed the Fund’s initial investment in such contracts.

● Government-Sponsored Entities Risk. Securities issued by government-sponsored entities may not be backed by the full faith and credit of the United States.

● High-Yield Securities Risk. Fixed income securities that are rated below investment grade (i.e., “junk bonds”) are subject to additional risk factors due to the speculative nature of these securities, such as increased possibility of default liquidation of the security, and changes in value based on public perception of the issuer.

● Initial Public Offering Risk. The market value of IPO shares may fluctuate considerably due to factors such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk.

● Interest Rate Risk. The market value of fixed income securities changes in response to interest rate changes and other factors. Generally, prices of fixed income securities will increase as interest rates fall and will decrease as interest rates rise. It is likely there will be less governmental action in the near future to maintain low interest rates. The negative impact on fixed income securities from the resulting rate increases for that and other reasons could be swift and significant.

● Large Companies Risk. The securities of large capitalization companies may underperform other segments of the market because such companies may be less responsive to competitive challenges and opportunities and may be unable to attain or maintain high growth rates during periods of economic expansion.

● Leverage and Short Sales Risk. Leverage is the practice of borrowing money to purchase securities. If the securities decrease in value, the Fund will suffer a greater loss than would have resulted without the use of leverage. A short sale will be successful if the price of the shorted security decreases, however, if the underlying security goes up in price during the period in which the short position is outstanding, the Fund will realize a loss. The risk on a short sale is unlimited because the Fund must buy the shorted security at the higher price to complete the transaction. Therefore, short sales may be subject to greater risks than investments in long positions.

● Management Risk. The skill of the Adviser will play a significant role in the Fund’s ability to achieve its investment objective. The Fund’s ability to achieve its investment objective depends on the investment skill and ability of the Adviser and on its ability to correctly identify economic trends.

● Market Risk. The value of the Fund’s shares will fluctuate as a result of the movement of the overall stock market or the value of the individual securities held by the Fund, and you could lose money.

● Master Limited Partnership Risk. Investments in securities (units) of MLPs involve risks that differ from an investment in common stock. To the extent that an MLP’s interests are all in a particular industry, the MLP will be negatively impacted by economic events adversely impacting that industry. Additionally, holders of the units of MLPs have more limited control and limited rights to vote on matters affecting the partnership. There are also certain tax risks associated with an investment in units of MLPs.

● Mortgage-Related and Other Asset-Backed Securities Risk. Generally, rising interest rates tend to extend the duration of fixed rate mortgage-related securities, making them more sensitive to changes in interest rates. As a result, in a period of rising interest rates, if the Fund holds mortgage-related securities, it may exhibit additional volatility. This is known as extension risk. In addition, adjustable and fixed rate mortgage-related securities are subject to prepayment risk. When interest rates decline, borrowers may pay off their mortgages sooner than expected. This can reduce the returns of the Fund because it may have to reinvest that money at the lower prevailing interest rates. The risk of default is generally higher in mortgage-related investments that include sub-prime mortgages. Asset-backed securities are subject to risks similar to those associated with mortgage-related securities.

● Options Risk. Purchasing and writing put and call options are highly specialized activities and entail greater than ordinary investment risks. The Fund may not fully benefit from or may lose money on an option if changes in its value do not correspond as anticipated to changes in the value of the underlying securities.

● Portfolio Turnover Risk. A high portfolio turnover rate (100% or more on an annualized basis) increases the Fund’s transaction costs (including brokerage commissions and dealer costs), which adversely impacts the Fund’s performance. Higher portfolio turnover may result in the realization of more short-term capital gains than if the Fund had lower portfolio turnover.

● Preferred Stock Risk. Preferred stocks may be more volatile than fixed income securities and are more correlated with the issuer’s underlying common stock than fixed income securities. Additionally, the dividend on a preferred stock may be changed or omitted by the issuer.

● Real Estate and REIT Concentration Risk. The Fund is vulnerable to the risks of the real estate industry, such as the risk that a decline in rental income may occur because of extended vacancies, the failure to collect rents, increased competition from other properties, or poor management. The value and performance of REITs depends on how well the underlying properties owned by the REIT are managed. In addition, the value of an individual REIT’s securities can decline if the REIT fails to continue qualifying for special tax treatment. Investments in REITs may involve duplication of management fees and other expenses.

● Rule 144A Securities Risk. The market for Rule 144A securities typically is less active than the market for publicly-traded securities. Rule 144A securities carry the risk that the liquidity of these securities may become impaired, making it more difficult for the Fund to sell these bonds.

● Sector Risk. To the extent the Fund invests a significant portion of its assets in the securities of companies in the same sector of the market, the Fund is more susceptible to economic, political, regulatory and other occurrences influencing those sectors.

● Small and Medium Companies Risk. Investing in securities of small and medium capitalization companies may involve greater volatility than investing in larger and more established companies because small and medium capitalization companies can be subject to more abrupt or erratic share price changes than larger, more established companies.

● Swaps Risk. In a swap transaction, one party agrees to pay the other party an amount equal to the return, based upon an agreed-upon notional value, of a defined underlying asset or a non-asset reference (such as an index) during a specified period of time. In return, the other party would make periodic payments based on a fixed or variable interest rate or on the return from a different underlying asset or non-asset reference based upon an agreed-upon notional value. Swaps could result in losses if the underlying asset or reference does not perform as anticipated. The value of swaps, like many other derivatives, may move in unexpected ways and may result in losses for the Fund. Such transactions can have the potential for unlimited losses.

Performance Information

The Fund was reorganized following the close of business on April 28, 2017, to acquire the assets and liabilities of the Orinda Income Opportunities Fund, a series of Advisors Series Trust (the “Predecessor Fund”), in exchange for shares of the Fund. Accordingly, the Fund is the successor to the Predecessor Fund, and the following performance information shown prior to May 1, 2017, is that of the Predecessor Fund. The Fund has an investment objective, strategies and policies substantially similar to the Predecessor Fund, which was also advised by the Adviser.

The following information provides some indication of the risks of investing in the Fund. The bar chart shows changes in the Class I performance from year to year. The table shows how the Fund’s average annual returns for 1-year, 5-year and since inception periods compare with those of broad measures of market performance. The Fund’s past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available at www.orindafunds.com or by calling the Fund toll-free at 1-855-467-4632 (855-4ORINDA).

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance of the Fund (for the periods reflected in the chart above):

Best Quarter:	13.63% (quarter ended March 31, 2019)
Worst Quarter:	-9.55% (quarter ended December 31, 2018)

Average Annual Total Returns (For the periods ended December 31, 2019)

The table below compares the average annual total returns for the Fund before taxes for the past calendar year, the past five calendar years, and since inception periods to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Total Returns - Orinda - Orinda Income Opportunities Fund		1 Year	5 Years	Since Inception		Inception Date
Class I		20.95%	4.72%	4.78%	[1]	Jun. 28, 2013
Class I | After Taxes on Distributions	[2]	19.19%	2.82%	2.83%	[1]	Jun. 28, 2013
Class I | After Taxes on Distributions and Sales	[3]	12.79%	2.96%	2.97%	[1]	Jun. 28, 2013
Class A		14.59%	3.34%	3.64%	[1]	Jun. 28, 2013
Class D		19.71%	3.71%	3.92%	[4]	Sep. 27, 2013
Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)		8.72%	3.05%	3.32%	[1]	Jun. 28, 2013
Bloomberg Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)		8.72%	3.05%	3.35%	[4]	Sep. 27, 2013

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses.

[1] The Predecessor Fund's Class I and Class A shares commenced operations on June 28, 2013.

[2] After-tax returns were calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown and after-tax returns shown are not relevant to those who hold their Fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts ("IRAs"). After-tax returns are shown only for Class I; after-tax returns for Class A and Class D will vary, to the extent each class has different expenses.

[3] In certain cases, the figure representing "Return After Taxes on Distributions and Sale of Fund Shares" may be higher than the other return figures for the same period, since a higher after-tax return results when a capital loss occurs upon redemption and provides an assumed tax deduction that benefits the investor.

[4] The Predecessor Fund's Class D shares commenced operations on September 27, 2013.

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Summit Global Investments | SGI U.S. Small Cap Equity Fund

SUMMARY SECTION     U.S. Small Cap Equity Fund

Investment Objective

The SGI U.S. Small Cap Equity Fund (for this section only, the “Fund”) seeks to outperform the Russell 2000^® Index over a market cycle while reducing overall volatility. There can be no guarantee that the Fund will achieve its investment objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may qualify for sales charge discounts on Class A Shares if you invest, or agree to invest in the future, at least $50,000 in the Fund. More information about these and other discounts is available from your financial professional, in the section of the Prospectus entitled “Shareholder Information — Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information — Reducing or Eliminating the Front-End Sales Charge.” Additionally, you may be required to pay commissions and/or other forms of compensation to a broker for transactions in Class I Shares of the Fund, which are not reflected in the tables or the examples below.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - Summit Global Investments - SGI U.S. Small Cap Equity Fund	Class I Shares	Class A Shares		Class C Shares
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	none	5.25%		none
Maximum Deferred Sales Charge (Load)	none	none	[1]	none
Maximum Sales Charge (Load) Imposed on Reinvested Dividends	none	none		none
Redemption Fee (as a percentage of amount redeemed, if applicable)	none	none		none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)      

Annual Fund Operating Expenses - Summit Global Investments - SGI U.S. Small Cap Equity Fund		Class I Shares	Class A Shares	Class C Shares
Management Fees		0.95%	0.95%	0.95%
Distribution and/or Service (12b-1) Fees		none	0.25%	1.00%
Other Expenses		0.45%	0.45%	0.45%
Acquired fund fees and expenses	[1]	0.52%	0.52%	0.52%
Total Annual Fund Operating Expenses		1.92%	2.17%	2.92%
Fee Waivers and/or Expense Reimbursements	[2]	(0.17%)	(0.17%)	(0.17%)
Total Annual Fund Operating Expenses after Fee Waivers and/or Expense Reimbursements		1.75%	2.00%	2.75%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Class A Shares or Class C Shares or $1,000,000 in the Class I Shares of the Fund and for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - Summit Global Investments - SGI U.S. Small Cap Equity Fund - USD ($)	One Year	Three Years	Five Years	Ten Years
Class I Shares	17,784	58,663	102,098	222,948
Class A Shares	717	1,153	1,614	2,884
Class C Shares	278	888	1,523	3,230

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. For the fiscal year ended August 31, 2019, the Fund’s portfolio turnover rate was 145% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund will invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities, primarily common stocks of U.S. issuers with small market capitalizations. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Index. The Russell 2000^® Index is a small cap stock market index measuring the performance of approximately 2,000 small cap U.S. companies. As of November 30, 2019, the median market capitalization of this index was $786 million and the largest stock was $9.1 billion. The Fund’s investments will generally consist of securities, which may include common stocks, preferred stocks, warrants to acquire common stock, and securities convertible into common stock. The Fund purchases equity securities traded in the U.S. on registered exchanges or the over-the-counter market. The Fund may also invest in other registered investment companies, including exchange-traded funds (“ETFs”), and may invest in real estate investment trusts (“REITs”).

The Adviser attempts to lower the Fund’s market risk by investing in U.S. equity securities that lower the overall volatility of the Fund’s portfolio as compared to the Russell 2000^® Index. Volatility is a statistical measurement of the magnitude of up and down fluctuations in the value of a financial instrument or index. The Fund invests in stocks that often exhibit less volatile stock price patterns, strengthening business metrics (i.e., earnings, debt, return on assets, competition, customers, industry, etc.) and quantitative factors such as earnings variability, leverage, volatility, price/book, price/cash flow, etc. In addition, the Adviser reviews the idiosyncratic risks associated with each stock if these risks are deemed elevated with increased downside risks, due to environmental, social and/or governance (“ESG”) issues. The Adviser selects securities for the Fund that it anticipates will produce a portfolio with less volatility with more capital protection and consistent returns. While the Adviser attempts to manage the Fund’s volatility, there is no guarantee that the strategy will be successful or that the Fund’s portfolio will not experience periods of volatility.

The Fund may sell a stock if the Adviser identifies fundamental, ESG, or legal risks and/or if the risk/return ranking declines due to increasing risk and/or decreasing return potential. The Fund may also decrease weight in an investment for risk control purposes.

Principal Risks

Loss of money is a risk of investing in the Fund. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The Fund’s principal risks are presented in alphabetical order to facilitate finding particular risks and comparing them with other funds. Each risk summarized below is considered a “principal risk” of investing in the Fund, regardless of the order in which it appears. Different risks may be more significant at different times depending on market conditions or other factors.

■ Common Stock Risk. Investments in common stocks are subject to market, economic and business risks that will cause their price to fluctuate over time. Therefore, an investment in the Fund may be more suitable for long-term investors who can bear the risk of these fluctuations.

■ Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities

■ Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to Fund assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the investment adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent Fund investors from purchasing, redeeming or exchanging shares or receiving distributions. The Fund and its investment adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders.

■ Environmental, Social and Governance Investing Risk. ESG investing risk is the risk stemming from the environmental, social and governance factors that the Fund applies in selecting securities. The Fund intends to invest in companies with measurable high ESG ratings relative to their sector peers, and screen out particular companies that do not meet its ESG criteria. This may affect the Fund’s exposure to certain companies or industries and cause the Fund to forego certain investment opportunities. The Fund’s results may be lower than other funds that do not seek to invest in companies based on ESG ratings and/or screen out certain companies or industries. The Fund seeks to identify companies that it believes may have a societal impact outcome, but investors may differ in their views of what constitutes positive or negative societal impact outcomes. As a result, the Fund may invest in companies that do not reflect the beliefs and values of any particular investor.

■ High Portfolio Turnover Risk. The risk that when investing on a shorter-term basis, the Fund may as a result trade more frequently and incur higher levels of brokerage fees and commissions and cause higher levels of current tax liability to shareholders of the Fund. A portfolio turnover rate of 100% is considered to be high. The Adviser may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

■ Investment Companies and ETFs Risk. Investing in other investment companies, including ETFs, may result in duplication of expenses, including advisory fees, in addition to the Fund’s own expenses. The risk of owning an investment company or ETF generally reflects the risks of owning the underlying investments the investment company or ETF holds. The Fund may incur brokerage fees in connection with its purchase of ETF shares. Certain ETFs may be thinly traded and experience large spreads between the “ask” price quoted by a seller and the “bid” price offered by a buyer.

■ Low Volatility Risk. Although subject to the risks of common stocks, low volatility stocks are seen as having a lower risk profile than the overall markets. However, a portfolio comprised of low volatility stocks may not produce investment exposure that has lower variability to changes in such stocks’ price levels. Investing in low volatility stocks may limit the Fund’s gains in rising markets.

■ Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.

■ Market Risk. The NAV of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes will produce less volatility, there is no guarantee that the stocks will perform as expected.

■ Opportunity Risk. As with all mutual funds, the Fund is subject to the risk of missing out on an opportunity because the assets necessary to take advantage of it are tied up in less advantageous investments.

■ REITs Risk. The Fund’s investments in REITs may be affected by economic forces and other factors related to the real estate industry. These risks include possible declines in the value of real estate, possible lack of availability of mortgage funds and unexpected vacancies of properties. REITs are also subject to heavy cash flow dependency, defaults by borrowers, self-liquidating interest rate risks (especially mortgage REITs) and liquidity risk. REITs that invest in real estate mortgages are also subject to prepayment risk. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume, engage in dilutive offerings, and may be subject to more abrupt or erratic price movements than the securities of larger companies. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

■ Small Cap Risk. Stocks of small companies may be more volatile than, and not as readily marketable as, those of larger companies. Small companies may also have limited product lines, markets or financial resources and may be dependent on relatively small or inexperienced management groups. Additionally, the trading volume of small company securities may make them more difficult to sell than those of larger companies. Moreover, the lack of an efficient market for the securities may make them difficult to value.

■ Warrants Risk. The purchase of warrants involves the risk that the Fund could lose the purchase value of a warrant if the right to subscribe to additional shares is not executed prior to the warrant’s expiration. Also, the purchase of warrants involves the risk that the effective price paid for the warrant added to the subscription price of the related security may exceed the value of the subscribed security’s market price such as when there is no movement in the level of the underlying security.

Performance Information

The chart below illustrates the performance of the Fund’s Class I Shares. The information shows the Fund’s performance for one year and provides some indication of the risks of investing in the Fund. The chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund’s performance would be reduced. Updated performance information may be obtained at www.sgiam.com or by calling 1-855-744-8500.

TOTAL RETURNS FOR THE CALENDAR YEARS ENDED DECEMBER 31 *

^* The returns in the bar chart are for Class I Shares. Class A Shares and Class C Shares would have substantially similar annual returns because each class of shares would have invested in the same portfolio of securities, and the annual returns would differ only to the extent that the classes have different expenses. The Fund’s Class A Shares are subject to a sales charge (load). Sales charges (loads) or account fees are not reflected in the bar chart and if these amounts were reflected, returns would be less than those shown.

Best and Worst Quarterly Performance (for the period reflected in the chart above):

Best Quarter: 10.94% (quarter ended March 31, 2019)
Worst Quarter: -19.35% (quarter ended December 31, 2018)

AVERAGE ANNUAL TOTAL RETURNS FOR THE PERIODS ENDED DECEMBER 31, 2019

The table below, which includes all applicable sales charges (loads) and account fees, compares the Fund’s Class I, Class A and Class C Shares average annual total returns for the periods indicated to the average annual total returns of a broad-based securities market index for the same periods. Past performance (before and after taxes) is not necessarily an indicator of how the Fund will perform in the future.

Average Annual Total Returns - Summit Global Investments - SGI U.S. Small Cap Equity Fund		1 Year	Since Inception	Inception Date
Class I Shares		20.66%	10.30%	Mar. 31, 2016
Class I Shares | After Taxes on Distributions	[1]	20.32%	8.91%	Mar. 31, 2016
Class I Shares | After Taxes on Distributions and Sales	[1]	12.42%	7.69%	Mar. 31, 2016
Class A Shares	[2]	14.06%	8.51%	Mar. 31, 2016
Class C Shares		19.43%	9.23%	Mar. 31, 2016
Russell 2000® Index (reflects reinvestment of dividends and no deductions for fees, expenses or taxes)		25.52%	12.91%	Mar. 31, 2016

[1] A contingent deferred sales charge of 1.00% is assessed on certain redemptions of Class A Shares made within 18 months after purchase where no initial sales charge was paid at the time of purchase as part of an investment of $1,000,000 or more.

[1] Acquired Fund Fees and Expenses are indirect fees and expenses that the Fund incurs from investing in the shares of other mutual funds, including money market funds and exchange-traded funds. Please note that the amount of Total Annual Fund Operating Expenses shown in the above table will differ from the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does not include indirect expenses such as Acquired Fund Fees and Expenses.

[2] Summit Global Investments, LLC (the "Adviser"), the Fund's investment adviser, has contractually agreed to waive management fees and reimburse expenses through February 28, 2021 to the extent that Total Annual Fund Operating Expenses (excluding certain items discussed below) exceed 1.23%, 1.48% and 2.23% of the Fund's average daily net assets attributable to Class I Shares, Class A and Class C Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and are expected to cause net Total Annual Fund Operating Expenses to exceed 1.23%, 1.48% or 2.23%, as applicable: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation may not be terminated before February 28, 2021 without the approval of the Board of Directors of The RBB Fund, Inc. (the "Company"). If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 1.23%, 1.48% and 2.23% of the Fund's average daily net assets attributable to Class I Shares, Class A Shares and Class C Shares, respectively, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts ("IRAs"). Class I Shares, Class A Shares and Class C Shares commenced operations on March 31, 2016.

[2] Effective as of January 1, 2018, Class A Shares of the Fund are charged a 5.25% sales load. Accordingly, performance information for Class A Shares for periods prior to January 1, 2018 has been restated to reflect the effect of the sales load.